1: $n$ – Integer Input: On entry: $n$ , the number of points.

Constraint: $n \geq 0$ .
2: $x [n]$ – const double Input: On entry: the argument $x_{i}$ of the function, for $i = 1, 2, \dots, n$ .
3: $f [n]$ – double Output: On exit: $Q (x_{i})$ , the function values.
4: $fail$ – NagError * Input/Output: The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

6 Error Indicators and Warnings

NE_ALLOC_FAIL: Dynamic memory allocation failed.
See Section 3.1.2 in the Introduction to the NAG Library CL Interface for further information.
NE_BAD_PARAM: On entry, argument $⟨ value ⟩$ had an illegal value.
NE_INT: On entry, $n = ⟨ value ⟩$ .
Constraint: $n \geq 0$ .
NE_INTERNAL_ERROR: An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
See Section 7.5 in the Introduction to the NAG Library CL Interface for further information.
NE_NO_LICENCE: Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library CL Interface for further information.

7 Accuracy

Because of its close relationship with

erfc

the accuracy of this function is very similar to that in s15adc. If

ε

and

δ

are the relative errors in result and argument, respectively, then in principle they are related by

| ε | ≃ | \frac{x e^{- x^{2} / 2}}{\sqrt{2 π} Q (x)} δ | .

For

x

negative or small positive this factor is always less than

1

and accuracy is mainly limited by machine precision. For large positive

x

we find

ε \sim x^{2} δ

and hence to a certain extent relative accuracy is unavoidably lost. However, the absolute error in the result,

E

, is given by

| E | ≃ | \frac{x e^{- x^{2} / 2}}{\sqrt{2 π}} δ |

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

x

s15aqc is not threaded in any implementation.

None.

This example reads values of the argument

x

from a file, evaluates the function at each value of

x

and prints the results.

s15aq: FL CL CPP AD