This version of this document is no longer maintained. For the latest documentation, see http://www.qnx.com/developers/docs. |
Complementary error function
#include <math.h> double erfc ( double x ); float erfcf ( float x );
libm
Use the -l m option to qcc to link against this library.
The erfc() and erfcf() functions calculate the complementary error function of x (i.e. the result of the error function, erf(), subtracted from 1.0). This is useful because the error function isn't very accurate when x is large.
The erf() function computes:
This equality is true: erfc(-x) = 2 - erfc(x)
The value of the error function, or NAN if x is NAN.
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 |