NAG CL Interface
g01rtc returns the value of the derivative of the Landau density function.
The function may be called by the names: g01rtc, nag_stat_pdf_landau_deriv or nag_prob_der_landau.
evaluates an approximation to the derivative
of the Landau density function given by
is described in g01mtc
, 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
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
g01rtc is not threaded in any implementation.
This example evaluates at , and prints the results.