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/* -- translated by f2c (version 19940927).
You must link the resulting object file with the libraries:
-lf2c -lm (in that order)
*/
#include "f2c.h"
doublereal slaran_(integer *iseed)
{
/* System generated locals */
real ret_val;
/* Local variables */
static integer it1, it2, it3, it4;
/* -- LAPACK auxiliary routine (version 2.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
February 29, 1992
Purpose
=======
SLARAN returns a random real number from a uniform (0,1)
distribution.
Arguments
=========
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 uses a multiplicative congruential method with modulus
2**48 and multiplier 33952834046453 (see G.S.Fishman,
'Multiplicative congruential random number generators with modulus
2**b: an exhaustive analysis for b = 32 and a partial analysis for
b = 48', Math. Comp. 189, pp 331-344, 1990).
48-bit integers are stored in 4 integer array elements with 12 bits
per element. Hence the routine is portable across machines with
integers of 32 bits or more.
=====================================================================
multiply the seed by the multiplier modulo 2**48
Parameter adjustments */
--iseed;
/* Function Body */
it4 = iseed[4] * 2549;
it3 = it4 / 4096;
it4 -= it3 << 12;
it3 = it3 + iseed[3] * 2549 + iseed[4] * 2508;
it2 = it3 / 4096;
it3 -= it2 << 12;
it2 = it2 + iseed[2] * 2549 + iseed[3] * 2508 + iseed[4] * 322;
it1 = it2 / 4096;
it2 -= it1 << 12;
it1 = it1 + iseed[1] * 2549 + iseed[2] * 2508 + iseed[3] * 322 + iseed[4]
* 494;
it1 %= 4096;
/* return updated seed */
iseed[1] = it1;
iseed[2] = it2;
iseed[3] = it3;
iseed[4] = it4;
/* convert 48-bit integer to a real number in the interval (0,1) */
ret_val = ((real) it1 + ((real) it2 + ((real) it3 + (real) it4 *
2.44140625e-4f) * 2.44140625e-4f) * 2.44140625e-4f) *
2.44140625e-4f;
return ret_val;
/* End of SLARAN */
} /* slaran_ */
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