NAG Library Routine Document
G01FTF returns the value of the inverse of the Landau distribution function, via the routine name.
|REAL (KIND=nag_wp) G01FTF
G01FTF evaluates an approximation to the inverse
of the Landau distribution function given by
is described in G01ETF
), using either linear or quadratic interpolation or rational approximations which mimic the asymptotic behaviour. Further details can be found in Kölbig and Schorr (1984)
It can also be used to generate Landau distributed random numbers in the range .
Kölbig K S and Schorr B (1984) A program package for the Landau distribution Comp. Phys. Comm. 31 97–111
- 1: X – REAL (KIND=nag_wp)Input
On entry: the argument of the function.
- 2: IFAIL – INTEGERInput/Output
must be set to
. If you are unfamiliar with this parameter you should refer to Section 3.3
in the Essential Introduction for details.
For environments where it might be inappropriate to halt program execution when an error is detected, the value
is recommended. If the output of error messages is undesirable, then the value
is recommended. Otherwise, if you are not familiar with this parameter, the recommended value is
. When the value is used it is essential to test the value of IFAIL on exit.
unless the routine detects an error or a warning has been flagged (see Section 6
6 Error Indicators and Warnings
If on entry
, explanatory error messages are output on the current error message unit (as defined by X04AAF
Errors or warnings detected by the routine:
At least significant digits are correct. Such accuracy is normally considered to be adequate for applications in large scale Monte–Carlo simulations.
This example evaluates at , and prints the results.
9.1 Program Text
Program Text (g01ftfe.f90)
9.2 Program Data
Program Data (g01ftfe.d)
9.3 Program Results
Program Results (g01ftfe.r)