# Difference between revisions of "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 (3.1415926535897932);`

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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