*Complementary error function*

#include <math.h> double erfc ( doublex); float erfcf ( floatx); long double erfcl( long doublex);

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

`libm`

Use the ` -l m` option to

The *erfc()*, *erfcf()*, and *erfcl()*
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.
For a correct value that would cause an underflow, these functions return 0.0.

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 |