https://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&feed=atom&action=historyTAChart Tutorial: Function Series - Revision history2024-03-29T07:43:28ZRevision history for this page on the wikiMediaWiki 1.35.6https://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=133386&oldid=prevTrev: Fixed syntax highlighting2020-02-29T01:21:38Z<p>Fixed syntax highlighting</p>
<a href="//wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=133386&oldid=124330">Show changes</a>Trevhttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=124330&oldid=prevWp: /* Plotting y = tan(x) */ Avoid "Lazarus trunk", update to new event OnExtentValidate2019-04-19T12:20:38Z<p><span dir="auto"><span class="autocomment">Plotting y = tan(x): </span> Avoid "Lazarus trunk", update to new event OnExtentValidate</span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:20, 19 April 2019</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This chart, now, is perfect. </div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This chart, now, is perfect. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>It should be mentioned, however, that the code in the <code>FormCreate</code> procedure is too specific and is correct only for our x axis range from -10 to 10. Suppose the user could zoom out or could change the axis limits in some other way. Then these domain exclusions may not be appropriate any longer. Therefore, you should provide a more general method, maybe "<code>UpdateDomainExclusions</code>", and call it where appropriate. The first idea would be to use the chart's <code>OnExtentChanged</code> event. Without going into details, however, this may cause a hang under some circumstances because this event occurs after drawing of the chart. In <del class="diffchange diffchange-inline">the svn version of </del>Lazarus, however, there is a new event <code><del class="diffchange diffchange-inline">OnExtentChanging</del></code> which is better suited because it is called before drawing. If you <del class="diffchange diffchange-inline">prefer the release </del>version you could use the event handler for <code>TChart.OnAfterDrawBackwall</code> although its name is not intuitive for this purpose. Don't forget to call <code>DomainExclusions.Clear</code> to avoid adding the same points again and again.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>It should be mentioned, however, that the code in the <code>FormCreate</code> procedure is too specific and is correct only for our x axis range from -10 to 10. Suppose the user could zoom out or could change the axis limits in some other way. Then these domain exclusions may not be appropriate any longer. Therefore, you should provide a more general method, maybe "<code>UpdateDomainExclusions</code>", and call it where appropriate. The first idea would be to use the chart's <code>OnExtentChanged</code> event. Without going into details, however, this may cause a hang under some circumstances because this event occurs after drawing of the chart. In Lazarus <ins class="diffchange diffchange-inline">v2.1 or newer</ins>, however, there is a new event <code><ins class="diffchange diffchange-inline">OnExtentValidate</ins></code> which is better suited because it is called before <ins class="diffchange diffchange-inline">any </ins>drawing. If you <ins class="diffchange diffchange-inline">stick to an older </ins>version you could use the event handler for <code>TChart.OnAfterDrawBackwall</code> although its name is not intuitive for this purpose. Don't forget to call <code>DomainExclusions.Clear</code> to avoid adding the same points again and again.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td></tr>
</table>Wphttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=123855&oldid=prevWp: /* Plotting y = ln(x) */ Explain open domain exclusion intervals2019-03-22T10:29:04Z<p><span dir="auto"><span class="autocomment">Plotting y = ln(x): </span> Explain open domain exclusion intervals</span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:29, 22 March 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l161" >Line 161:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries8.png]]</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries8.png]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>But when we run the program it crashes because of a floating point exception! Where does that come from? Our x axis starts at -10, and the logarithmic function can be calculated only for positive x values. What can be done against that? The answer is domain exclusions, again. We just forbid calculation of the function for negative values and for <code>x = 0</code>. This can be achieved by adding a range from -INF to 0 to the series' domain exclusions. The method <code>AddRange</code> also includes the end points of the interval, so we need no special treatment for <code>x = 0</code>. We modify the form's <code>OnCreate</code> event handler as follows:</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>But when we run the program it crashes because of a floating point exception! Where does that come from? Our x axis starts at -10, and the logarithmic function can be calculated only for positive x values. What can be done against that? The answer is domain exclusions, again. We just forbid calculation of the function for negative values and for <code>x = 0</code>. This can be achieved by adding a range from -INF to 0 to the series' domain exclusions. The method <code>AddRange</code><ins class="diffchange diffchange-inline">, by default, </ins>also includes the end points of the interval, so we need no special treatment for <code>x = 0</code>. We modify the form's <code>OnCreate</code> event handler as follows:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l179" >Line 179:</td>
<td colspan="2" class="diff-lineno">Line 179:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Now the program runs fine.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Now the program runs fine.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del class="diffchange diffchange-inline">One thing </del>to <del class="diffchange diffchange-inline">mention </del>is <del class="diffchange diffchange-inline">the property </del><code><del class="diffchange diffchange-inline">Epsilon</del></code> <del class="diffchange diffchange-inline">of </del>the <code><del class="diffchange diffchange-inline">DomainExclusions</del></code>. This <del class="diffchange diffchange-inline">value controls </del>the <del class="diffchange diffchange-inline">distance between </del>the <del class="diffchange diffchange-inline">endpoint </del>of the <del class="diffchange diffchange-inline">excluded </del>interval <del class="diffchange diffchange-inline">and the last drawn function point. Its default value </del>of <code><del class="diffchange diffchange-inline">1e-6</del></code> <del class="diffchange diffchange-inline">is fine for most cases, but you may want </del>to <del class="diffchange diffchange-inline">increase it for infinity-type discontinuities (such as </del><code><del class="diffchange diffchange-inline">y = tan(x)</del></code><del class="diffchange diffchange-inline">), or decrease it to approximate open excluded intervals. An example </del>for <del class="diffchange diffchange-inline">the latter case is the function </del><code>y = sqrt(x)</code> <del class="diffchange diffchange-inline">which </del>is <del class="diffchange diffchange-inline">not defined for negative numbers</del>, <del class="diffchange diffchange-inline">but </del>is <del class="diffchange diffchange-inline">defined at </del><code><del class="diffchange diffchange-inline">x = 0</del></code> <del class="diffchange diffchange-inline">(unlike the logarithm function); currently the domain exclusions </del>of <del class="diffchange diffchange-inline">TAChart are closed intervals only; therefore, </del>the <del class="diffchange diffchange-inline">point </del><code><del class="diffchange diffchange-inline">x = 0</del></code> <del class="diffchange diffchange-inline">cannot be </del>drawn <del class="diffchange diffchange-inline">exactly for </del><code><del class="diffchange diffchange-inline">y = sqrt(x)</del></code>.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">What if we would want to plot the function <code>y = sqrt(x)</code>? There is a subtle difference </ins>to <ins class="diffchange diffchange-inline"><code>y = log(x)</code>: while both functions cannot be calculated for <code>x < 0</code>, <code>sqrt(x)</code> </ins>is <ins class="diffchange diffchange-inline">defined also at </ins><code><ins class="diffchange diffchange-inline">x = 0</ins></code><ins class="diffchange diffchange-inline">, i.e. </ins>the <ins class="diffchange diffchange-inline">point </ins><code><ins class="diffchange diffchange-inline">x = 0</ins></code> <ins class="diffchange diffchange-inline">must be excluded from the domain exclusion interval</ins>. This <ins class="diffchange diffchange-inline">can be achieved in </ins>the <ins class="diffchange diffchange-inline"><code>AddRange</code> method by specifying </ins>the <ins class="diffchange diffchange-inline">open end(s) </ins>of the interval <ins class="diffchange diffchange-inline">in an optional third parameter set </ins>of <code><ins class="diffchange diffchange-inline">TIntervalOption = (ioOpenStart, ioOpenEnd)</ins></code><ins class="diffchange diffchange-inline">. The correct code </ins>to <ins class="diffchange diffchange-inline">set up the </ins><code><ins class="diffchange diffchange-inline">DomainExclusions</ins></code> for <code>y = sqrt(x)</code><ins class="diffchange diffchange-inline">, therefore, </ins>is</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline"><source></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline"> SqrtXSeries.DomainExclusions.AddRange(NegInfinity, 0</ins>, <ins class="diffchange diffchange-inline">[ioOpenEnd]);</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline"></source></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">One thing to mention </ins>is <ins class="diffchange diffchange-inline">the property </ins><code><ins class="diffchange diffchange-inline">Epsilon</ins></code> of the <code><ins class="diffchange diffchange-inline">DomainExclusions</ins></code><ins class="diffchange diffchange-inline">. This value controls the distance between the endpoint of the excluded interval and the last </ins>drawn <ins class="diffchange diffchange-inline">function point (of a closed excluded interval). Its default value of </ins><code><ins class="diffchange diffchange-inline">1e-6</ins></code> <ins class="diffchange diffchange-inline">is fine for most cases, but you may want to change it if it does not lead to correct results</ins>. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries9.png]]</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries9.png]]</div></td></tr>
</table>Wphttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=123800&oldid=prevWp: /* Plotting y = ln(x) */ Fix DomainExclusions for the case Epsilon=02019-03-20T17:04:06Z<p><span dir="auto"><span class="autocomment">Plotting y = ln(x): </span> Fix DomainExclusions for the case Epsilon=0</span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:04, 20 March 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l161" >Line 161:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries8.png]]</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries8.png]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>But when we run the program it crashes because of a floating point exception! Where does that come from? Our x axis starts at -10, and the logarithmic function can be calculated only for positive x values. What can be done against that? The answer is domain exclusions, again. We just forbid calculation of the function for negative values and for x=0. This can be achieved by adding a range from -INF to 0 to the series' domain exclusions. The method <code>AddRange</code> also includes the end points of the interval, so we need no special treatment for x=0. We modify the form's <code>OnCreate</code> event handler as follows:</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>But when we run the program it crashes because of a floating point exception! Where does that come from? Our x axis starts at -10, and the logarithmic function can be calculated only for positive x values. What can be done against that? The answer is domain exclusions, again. We just forbid calculation of the function for negative values and for <ins class="diffchange diffchange-inline"><code></ins>x = 0<ins class="diffchange diffchange-inline"></code></ins>. This can be achieved by adding a range from -INF to 0 to the series' domain exclusions. The method <code>AddRange</code> also includes the end points of the interval, so we need no special treatment for <ins class="diffchange diffchange-inline"><code></ins>x = 0<ins class="diffchange diffchange-inline"></code></ins>. We modify the form's <code>OnCreate</code> event handler as follows:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td></tr>
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<td colspan="2" class="diff-lineno">Line 179:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Now the program runs fine.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Now the program runs fine.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>One thing to mention is the property <code>Epsilon</code> of the <code>DomainExclusions</code>. This value controls the distance between the endpoint of the excluded interval and the last drawn function point. Its default value of <code>1e-6</code> is fine for most cases, but you may want to increase it for infinity-type discontinuities (such as <code>y = tan(x)</code>), or decrease it to <del class="diffchange diffchange-inline">model </del>open excluded intervals. An example for the latter case is the function <code>y = sqrt(x)</code> which is not defined for negative numbers, but is defined at <code>x = 0</code> (unlike the logarithm function); <del class="diffchange diffchange-inline">in this case </del>the domain <del class="diffchange diffchange-inline">exclusion should not contain </del><code>x = 0</code><del class="diffchange diffchange-inline">, but since the intervals of </del><code><del class="diffchange diffchange-inline">DomainExclusions</code> are always closed you can show this point in the chart by setting <code>Epsilon </del>= <del class="diffchange diffchange-inline">0</del></code>.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>One thing to mention is the property <code>Epsilon</code> of the <code>DomainExclusions</code>. This value controls the distance between the endpoint of the excluded interval and the last drawn function point. Its default value of <code>1e-6</code> is fine for most cases, but you may want to increase it for infinity-type discontinuities (such as <code>y = tan(x)</code>), or decrease it to <ins class="diffchange diffchange-inline">approximate </ins>open excluded intervals. An example for the latter case is the function <code>y = sqrt(x)</code> which is not defined for negative numbers, but is defined at <code>x = 0</code> (unlike the logarithm function); <ins class="diffchange diffchange-inline">currently </ins>the domain <ins class="diffchange diffchange-inline">exclusions of TAChart are closed intervals only; therefore, the point </ins><code>x = 0</code> <ins class="diffchange diffchange-inline">cannot be drawn exactly for </ins><code><ins class="diffchange diffchange-inline">y </ins>= <ins class="diffchange diffchange-inline">sqrt(x)</ins></code>.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries9.png]]</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries9.png]]</div></td></tr>
</table>Wphttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=104750&oldid=prevDjzepi at 14:15, 3 November 20162016-11-03T14:15:37Z<p></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:15, 3 November 2016</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1" >Line 1:</td>
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<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{TAChart Tutorial: Function Series}}</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Introduction ==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Introduction ==</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>procedure TForm1.UpdateDomainExclusions;</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>procedure TForm1.UpdateDomainExclusions;</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>var</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>var</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> ex: TDoubleRect;</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> ex: TDoubleRect; <ins class="diffchange diffchange-inline">// unit TAChartUtils.pas</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> x: Integer;</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> x: Integer;</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>begin</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>begin</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Source code ==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Source code ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The source code for the final version of this tutorial project can be found in the folder ''tutorials/func_series'' of the TAChart installation.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The source code for the final version of this tutorial project can be found in the folder ''tutorials/func_series'' of the TAChart installation.</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2"> </td></tr>
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<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">[[Category:TAChart]]</del></div></td><td colspan="2"> </td></tr>
</table>Djzepihttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=63902&oldid=prevJwdietrich at 22:55, 11 November 20122012-11-11T22:55:36Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Tutorials]]</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Tutorials]]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Category:TAChart]]</ins></div></td></tr>
</table>Jwdietrichhttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=63529&oldid=prevWp: /* Introduction */ Add screenshot of final project version as a teaser2012-10-31T23:00:35Z<p><span dir="auto"><span class="autocomment">Introduction: </span> Add screenshot of final project version as a teaser</span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 23:00, 31 October 2012</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1" >Line 1:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Introduction ==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Introduction ==</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[File:FuncSeries10.png]]</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Did you work through the [[TAChart_Tutorial:_Getting_started|Getting started tutorial]]? In that tutorial we had used some mathematical functions to demonstrate the basic usage of TAChart by means of line series. Line series, however, is not the best choice for drawing mathematical functions. [[TAChart_documentation#FunctionSeries|<code>TFuncSeries</code>]] is much better suited to this purpose. This is a series type that -- at first sight -- looks like an ordinary line series. But in the background, it is completely different. It does not get its data from a ChartSource, but from a mathematical function. Whenever the series needs data it calls the handler for <code>OnCalculate</code> event where the user can pass the function values for an x value requested. This saves memory for storage of the function values. But most of all, it allows to calculate the function values, depending on zooming level and chart size, at sufficiently narrow intervals, such that the series curve is smooth even at high magnifications.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Did you work through the [[TAChart_Tutorial:_Getting_started|Getting started tutorial]]? In that tutorial we had used some mathematical functions to demonstrate the basic usage of TAChart by means of line series. Line series, however, is not the best choice for drawing mathematical functions. [[TAChart_documentation#FunctionSeries|<code>TFuncSeries</code>]] is much better suited to this purpose. This is a series type that -- at first sight -- looks like an ordinary line series. But in the background, it is completely different. It does not get its data from a ChartSource, but from a mathematical function. Whenever the series needs data it calls the handler for <code>OnCalculate</code> event where the user can pass the function values for an x value requested. This saves memory for storage of the function values. But most of all, it allows to calculate the function values, depending on zooming level and chart size, at sufficiently narrow intervals, such that the series curve is smooth even at high magnifications.</div></td></tr>
</table>Wphttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=63528&oldid=prevWp: /* Additional coordinate axes (TConstantLineSeries) */ Add reference to source code in folder tutorials/func_series2012-10-31T22:59:06Z<p><span dir="auto"><span class="autocomment">Additional coordinate axes (TConstantLineSeries): </span> Add reference to source code in folder tutorials/func_series</span></p>
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</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l193" >Line 193:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries10.png]]</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:FuncSeries10.png]]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">== Source code ==</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">The source code for the final version of this tutorial project can be found in the folder ''tutorials/func_series'' of the TAChart installation.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Tutorials]]</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Tutorials]]</div></td></tr>
</table>Wphttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=63527&oldid=prevWp: /* Plotting y = tan(x) */2012-10-31T22:28:29Z<p><span dir="auto"><span class="autocomment">Plotting y = tan(x)</span></span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 22:28, 31 October 2012</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l123" >Line 123:</td>
<td colspan="2" class="diff-lineno">Line 123:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This chart, now, is perfect. </div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This chart, now, is perfect. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>It should be mentioned, however, that the code in the <code>FormCreate</code> procedure is too specific and is correct only for our x axis range from -10 to 10. Suppose the user could zoom out or could change the axis limits in some other way. Then these domain exclusions may not be appropriate any longer. Therefore, you should provide a more general method, maybe "<code>UpdateDomainExclusions</code>", and call it where appropriate. The first idea would be to use the chart's <code>OnExtentChanged</code> event. Without going into details, however, this may cause a hang under some circumstances because this event occurs after drawing of the chart. In the svn version of Lazarus, however, there is a new event <code>OnExtentChanging</code> which is better suited because it is called before drawing. If you prefer the release version you could use the event handler for <code>TChart.<del class="diffchange diffchange-inline">OnDrawBackwall</del></code> although its name is not intuitive for this purpose. Don't forget to call <code>DomainExclusions.Clear</code> to avoid adding the same points again and again.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>It should be mentioned, however, that the code in the <code>FormCreate</code> procedure is too specific and is correct only for our x axis range from -10 to 10. Suppose the user could zoom out or could change the axis limits in some other way. Then these domain exclusions may not be appropriate any longer. Therefore, you should provide a more general method, maybe "<code>UpdateDomainExclusions</code>", and call it where appropriate. The first idea would be to use the chart's <code>OnExtentChanged</code> event. Without going into details, however, this may cause a hang under some circumstances because this event occurs after drawing of the chart. In the svn version of Lazarus, however, there is a new event <code>OnExtentChanging</code> which is better suited because it is called before drawing. If you prefer the release version you could use the event handler for <code>TChart.<ins class="diffchange diffchange-inline">OnAfterDrawBackwall</ins></code> although its name is not intuitive for this purpose. Don't forget to call <code>DomainExclusions.Clear</code> to avoid adding the same points again and again.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td></tr>
</table>Wphttps://wiki.freepascal.org/index.php?title=TAChart_Tutorial:_Function_Series&diff=63525&oldid=prevWp: /* Plotting y = tan(x) */2012-10-31T22:23:27Z<p><span dir="auto"><span class="autocomment">Plotting y = tan(x)</span></span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 22:23, 31 October 2012</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l123" >Line 123:</td>
<td colspan="2" class="diff-lineno">Line 123:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This chart, now, is perfect. </div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This chart, now, is perfect. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>It should be mentioned, however, that the code in the <code>FormCreate</code> procedure is too specific and is correct only for our x axis range from -10 to 10. Suppose the user could zoom out or could change the axis limits in some other way. Then these domain exclusions may not be appropriate any longer. Therefore, you should provide a more general method, maybe "<code>UpdateDomainExclusions</code>", and call it where appropriate. The first idea would be to use the chart's <code>OnExtentChanged</code> event. Without going into details, however, this may cause a hang under some circumstances because this event occurs after drawing of the chart. In the svn version of Lazarus, however, there is a new event <code>OnExtentChanging</code> which is better suited because it is called before drawing. If you prefer the release version you could use <del class="diffchange diffchange-inline">the </del>the event handler for <code>TChart.OnDrawBackwall</code> although its name is not intuitive for this purpose. Don't forget to call <code>DomainExclusions.Clear</code> to avoid adding the same points again and again.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>It should be mentioned, however, that the code in the <code>FormCreate</code> procedure is too specific and is correct only for our x axis range from -10 to 10. Suppose the user could zoom out or could change the axis limits in some other way. Then these domain exclusions may not be appropriate any longer. Therefore, you should provide a more general method, maybe "<code>UpdateDomainExclusions</code>", and call it where appropriate. The first idea would be to use the chart's <code>OnExtentChanged</code> event. Without going into details, however, this may cause a hang under some circumstances because this event occurs after drawing of the chart. In the svn version of Lazarus, however, there is a new event <code>OnExtentChanging</code> which is better suited because it is called before drawing. If you prefer the release version you could use the event handler for <code>TChart.OnDrawBackwall</code> although its name is not intuitive for this purpose. Don't forget to call <code>DomainExclusions.Clear</code> to avoid adding the same points again and again.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><source></div></td></tr>
</table>Wp