# Standard Functions

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1F - Standard Functions (author: Tao Yue, state: unchanged)

Pascal has several standard mathematical functions that you can utilize. For example, to find the value of sin of pi radians:

```value := sin (3.141592653589793238462643383);
```

Note that the sin function operates on angular measure stated in radians, as do all the trigonometric functions. If everything goes well, value should become 0.

Functions are called by using the function name followed by the argument(s) in parentheses. Standard Pascal functions include:

Function Description Argument type Return type
abs absolute value real or integer same as argument
arctan arctan in radians real or integer real
cos cosine of a radian measure real or integer real
exp e to the given power real or integer real
ln natural logarithm real or integer real
round round to nearest integer real integer
sin sin of a radian measure real or integer real
sqr square (power 2) real or integer same as argument
sqrt square root (power 1/2) real or integer real
trunc truncate (round down) real or integer integer

For ordinal data types (integer or char), where the allowable values have a distinct predecessor and successor, you can use these functions:

Function Description Argument type Return type
chr character with given ASCII value integer char
ord ordinal value integer or char integer
pred predecessor integer or char same as argument type
succ successor integer or char same as argument type

Real is not an ordinal data type! That's because it has no distinct successor or predecessor. What is the successor of 56.0? Is it 56.1, 56.01, 56.001, 56.0001?

However, for an integer 56, there is a distinct predecessor — 55 — and a distinct successor — 57.

The same is true of characters:

``` 'b'
Successor: 'c'
Predecessor: 'a'
```

The above is not an exhaustive list, as modern Pascal compilers include thousands of functions for all sorts of purposes. Check your compiler documentation for more.

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