NAG FL Interface
g01rtf returns the value of the derivative of the Landau density function.
|Real (Kind=nag_wp), Intent (In)
|C Header Interface
g01rtf_ (const double *x)
The routine may be called by the names g01rtf or nagf_stat_pdf_landau_deriv.
evaluates an approximation to the derivative
of the Landau density function given by
is described in g01mtf
, using piecewise approximation by rational functions. Further details can be found in Kölbig and Schorr (1984)
To obtain the value of
can be used.
Kölbig K S and Schorr B (1984) A program package for the Landau distribution Comp. Phys. Comm. 31 97–111
– Real (Kind=nag_wp)
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
Background information to multithreading can be found in the Multithreading
g01rtf is not threaded in any implementation.
This example evaluates at , and prints the results.