Defect in XSH erf

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        Defect report from : Loic Domaigne , personal interest

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@ page 0 line 0 section erf comment {erf}

Problem:

Edition of Specification (Year): 2003

Defect code :  2. Omission

Missing Example.

Action:

Computing the probability for a normal variate

This example shows how to use erf() to compute the probability 
that a normal variate assumes a value in the range [x1,x2] with x1<=x2.


#include <math.h>

double
Phi(const double x1,
    const double x2
    )
{
  return ( erf(x2*M_SQRT1_2) - erf(x1*M_SQRT1_2) ) / 2;
}