cc [flag ...] file ... -lm [library ...]
double erf(double x);
float erff(float x);
long double erfl(long double x);
double erfc(double x);
float erfcf(float x);
long double erfcl(long double x);
erfc, erfcf and erfcl return 1.0 - erf(x). They are provided because of the extreme loss of relative accuracy when erf(x) is called for large x and the result is subtracted from 1.0 (for example, for x = 5, 12 places are lost).
In the -Xt compilation mode, the error handling procedures may be changed with the function matherr.