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rand_init
This routine initializes, with up to 4 seeds, a randomn number sequence.
The generator being primed is an F90 port of an xorshift generator described
in Marsaglia, Journal of Statistical Software 2003, vol 8.
It has a theoretical period of
 .
Please refer to the ``Comment on Random Number Generator''
in the Fortran90 facilities guidelines.
Location in HEALPix directory tree:
src/f90/mod/rngmod.f90
FORMAT call rand_init(
rng_handle, [seed1, seed2, seed3, seed4]
)
ARGUMENTS
| name & dimensionality |
kind |
in/out |
description |
|---|
| |
|
|
|
|
rng_handle |
planck_rng |
OUT |
structure of type planck_rng
containing on output all information necessary to continue same random sequence. |
| seed1 (OPTIONAL) |
I4B |
IN |
first seed of the random sequence. Can be of arbitray
sign. If set to
zero or not provided will be replaced internally by a non-zero hard coded value. |
| seed2 (OPTIONAL) |
I4B |
IN |
second seed. Same properties as above |
| seed3 (OPTIONAL) |
I4B |
IN |
third seed. Same as above. |
| seed4 (OPTIONAL) |
I4B |
IN |
fourth seed. Same as above. |
EXAMPLE:
use rngmod
type(planck_rng) :: rng_handle
call rand_init(rng_handle, 12345, 6789012)
initiates a random sequence with the pair of seeds (12345, 6789012).
RELATED ROUTINESThis section lists the routines related to rand_init
-
planck_rng
- derived type describing RNG state
-
rand_gauss
- function which returns a random normal deviate.
-
rand_uni
- function which returns a random uniform deviate.
Eric Hivon
2010-06-18
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