NAG Library Routine Document
g01etf returns the value of the Landau distribution function , via the routine name.
|Real (Kind=nag_wp)||:: ||g01etf|
|Real (Kind=nag_wp), Intent (In)||:: ||x|C Header Interface
g01etf_ (const double *x)|
evaluates an approximation to the Landau distribution function
is described in g01mtf
, using piecewise approximation by rational functions. Further details can be found in Kölbig and Schorr (1984)
Kölbig K S and Schorr B (1984) A program package for the Landau distribution Comp. Phys. Comm. 31 97–111
- 1: – Real (Kind=nag_wp)Input
On entry: the argument of the function.
Error Indicators and Warnings
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.
Parallelism and Performance
g01etf is not threaded in any implementation.
This example evaluates at , and prints the results.
Program Text (g01etfe.f90)
Program Data (g01etfe.d)
Program Results (g01etfe.r)