The function may be called by the names: g01etc, nag_stat_prob_landau or nag_prob_landau.
3Description
g01etc evaluates an approximation to the Landau distribution function given by
where is described in g01mtc, using piecewise approximation by rational functions. Further details can be found in Kölbig and Schorr (1984).
4References
Kölbig K S and Schorr B (1984) A program package for the Landau distribution Comp. Phys. Comm.31 97–111
5Arguments
1: – doubleInput
On entry: the argument of the function.
6Error Indicators and Warnings
None.
7Accuracy
At least significant digits are usually correct, but occasionally only . Such accuracy is normally considered to be adequate for applications in experimental physics.
Because of the asymptotic behaviour of , which is of the order of , underflow may occur on some machines when is moderately large and negative.
8Parallelism and Performance
g01etc is not threaded in any implementation.
9Further Comments
None.
10Example
This example evaluates at , and prints the results.