Compute the error function of a number
#include <math.h> double erf ( double x ); float erff ( float x ); long double erfl ( long double x );
The erf(), erff(), and erfl()
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)
To check for error situations, use feclearexcept() and fetestexcept(). For example:
The value of the error function.
If x is: | These functions return: | Errors: |
---|---|---|
±0.0 | 0.0, with the same sign as x | — |
A value that would cause underflow | x | FE_UNDERFLOW |
±Inf | 1.0, with the same sign as x | — |
NaN | NaN | — |
These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |