erf

erf

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Calculates the error function of a floating-point number

 #include <math.h> double erf ( double x  ); float erff ( float x  ); long double erfl ( long double x  ); 

The function erf( ), called the error function, is associated with the Gaussian function or normal distribution. If the measured values of a given random variable conform to a normal distribution with the standard deviation s, then the probability that a single measurement has an error within ± a is erf( a / (s x 2) ).

The function erfc( ) is the complementary error function, defined as erfc(x) = 1 - erf(x).

Example

 /*  * Given a normal distribution with mean 0 and standard deviation 1,  * calculate the probability that the random variable is within the  * range [0, 1.125]  */ double sigma = 1.0;        // The standard deviation double bound = 1.125; double probability;        // probability that mean <= value <= bound probability = 0.5 * erf( bound / (sigma * sqrt(2.0)) ); 

See Also

erfc( )