public static double s15ac(
	double x
)

Public Shared Function s15ac ( _
	x As Double _
) As Double

public:
static double s15ac(
	double x
)

static member s15ac : 
        x : float -> float 

s15ac returns the value of the complement of the cumulative Normal distribution function, $Q\left(x\right)$.

s15ac evaluates an approximate value for the complement of the cumulative Normal distribution function The method is based on the fact that and it calls s15ad to obtain the necessary value of $\mathit{erfc}$, the complementary error function.

Abramowitz M and Stegun I A (1972) Handbook of Mathematical Functions (3rd Edition) Dover Publications

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Because of its close relationship with $\mathit{erfc}$ the accuracy of this method is very similar to that in s15ad. If $\epsilon$ and $\delta$ are the relative errors in result and argument, respectively, then in principle they are related by

For $x$ negative or small positive this factor is always less than one and accuracy is mainly limited by machine precision. For large positive $x$ we find $\epsilon \sim x^2\delta$ and hence to a certain extent relative accuracy is unavoidably lost. However the absolute error in the result, $E$, is given by

and since this factor is always less than one absolute accuracy can be guaranteed for all $x$.

None.

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This example reads values of the argument $x$ from a file, evaluates the function at each value of $x$ and prints the results.