/* -- translated by f2c (version 19940927).
You must link the resulting object file with the libraries:
-lf2c -lm (in that order)
*/
#include "f2c.h"
doublereal slarnd_(integer *idist, integer *iseed)
{
/* System generated locals */
real ret_val;
/* Builtin functions */
double log(doublereal), sqrt(doublereal), cos(doublereal);
/* Local variables */
static real t1, t2;
extern doublereal slaran_(integer *);
/* -- LAPACK auxiliary routine (version 2.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
September 30, 1994
Purpose
=======
SLARND returns a random real number from a uniform or normal
distribution.
Arguments
=========
IDIST (input) INTEGER
Specifies the distribution of the random numbers:
= 1: uniform (0,1)
= 2: uniform (-1,1)
= 3: normal (0,1)
ISEED (input/output) INTEGER array, dimension (4)
On entry, the seed of the random number generator; the array
elements must be between 0 and 4095, and ISEED(4) must be
odd.
On exit, the seed is updated.
Further Details
===============
This routine calls the auxiliary routine SLARAN to generate a random
real number from a uniform (0,1) distribution. The Box-Muller method
is used to transform numbers from a uniform to a normal distribution.
=====================================================================
Generate a real random number from a uniform (0,1) distribution
Parameter adjustments */
--iseed;
/* Function Body */
t1 = slaran_(&iseed[1]);
if (*idist == 1) {
/* uniform (0,1) */
ret_val = t1;
} else if (*idist == 2) {
/* uniform (-1,1) */
ret_val = t1 * 2.f - 1.f;
} else if (*idist == 3) {
/* normal (0,1) */
t2 = slaran_(&iseed[1]);
ret_val = sqrt(log(t1) * -2.f) * cos(t2 *
6.2831853071795864769252867663f);
}
return ret_val;
/* End of SLARND */
} /* slarnd_ */