erfc_inverse
Evaluates the real inverse complementary error function erfc-1 (x).
Synopsis
#include <imsl.h>
float imsl_f_erfc_inverse (float x)
The type double procedure is imsl_d_erfc_inverse.
Required Arguments
float x (Input)
Point at which the inverse complementary error function is to be evaluated. The argument x must be in the range 0 < x < 2.
Point at which the inverse complementary error function is to be evaluated. The argument x must be in the range 0 < x < 2.
Return Value
The value of the inverse complementary error function.
Description
The inverse complementary error function y = erfc-1 (x) is such that x = erfc (y) where
Figure 11, Plot of erfc-1(x)
Example
Evaluate the inverse complementary error function at x = 1/2.
#include <imsl.h>
#include <stdio.h>
int main()
{
float x = 0.5;
float ans;
ans = imsl_f_erf_inverse(x);
printf("inverse erf(%f) = %f\n", x, ans);
}
Output
inverse erfc(0.500000) = 0.476936
Alert Errors
IMSL_LARGE_ARG_UNDERFLOW | The argument x must not be so large that the result underflows. Very approximately, x should be less than |
where ɛ is the machine precision. |
Warning Errors
IMSL_LARGE_ARG_WARN | |x| should be less than where ɛ is the machine precision, to prevent the answer from being less accurate than half precision. |
Fatal Errors
IMSL_ERF_ALGORITHM | The algorithm failed to converge. |
IMSL_SMALL_ARG_OVERFLOW | The computation of must not overflow. |
IMSL_REAL_OUT_OF_RANGE | The function is defined only for 0 < x < 2. |
