erf(3M)

erf -- error function

Synopsis

   cc [flag ...] file ...  -lm [library ...] 
    
   #include <math.h> 
   
 
   double erf(double x); 
   
 
   double erfc(double x);

Description

erf returns the error function of x, defined as

erfc, which returns 1.0 - erf(x), is provided because of the extreme loss of relative accuracy if erf(x) is called for large x and the result subtracted from 1.0 (for example, for x = 5, 12 places are lost).

Errors

On systems that support IEEE NaN, if x is a quiet NaN, that value is returned. If x is a signaling NaN, a quiet NaN is returned and the invalid operation exception is raised. In either case, errno is set to EDOM.

In the -Xt compilation mode, the error handling procedures may be changed with the function matherr.

References

exp(3M), matherr(3M)