*Compute the error function of a number*

#include <math.h> double erf ( doublex); float erff ( floatx);

`x`- The number for which you want to compute the error function.

The erf() and erff() functions compute the following:

If `x` is large and the result of
erf() is subtracted from `1.0`,
the results aren't very accurate; use
erfc() instead.

This equality is true: erf(-`x`) = -erf(`x`)

The value of the error function, or NAN
if `x` is NAN.

Note:
If an error occurs, these functions return 0, but this is also a valid
mathematical result.
If you want to check for errors, set
`errno`
to 0, call the function, and then check `errno` again.
These functions don't change `errno` if no errors occurred.

Safety: | |
---|---|

Cancellation point | No |

Interrupt handler | No |

Signal handler | No |

Thread | Yes |