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Diffstat (limited to 'test/math/drand.c')
-rw-r--r-- | test/math/drand.c | 158 |
1 files changed, 0 insertions, 158 deletions
diff --git a/test/math/drand.c b/test/math/drand.c deleted file mode 100644 index 9eedf71fc..000000000 --- a/test/math/drand.c +++ /dev/null @@ -1,158 +0,0 @@ -/* drand.c - * - * Pseudorandom number generator - * - * - * - * SYNOPSIS: - * - * double y, drand(); - * - * drand( &y ); - * - * - * - * DESCRIPTION: - * - * Yields a random number 1.0 <= y < 2.0. - * - * The three-generator congruential algorithm by Brian - * Wichmann and David Hill (BYTE magazine, March, 1987, - * pp 127-8) is used. The period, given by them, is - * 6953607871644. - * - * Versions invoked by the different arithmetic compile - * time options DEC, IBMPC, and MIEEE, produce - * approximately the same sequences, differing only in the - * least significant bits of the numbers. The UNK option - * implements the algorithm as recommended in the BYTE - * article. It may be used on all computers. However, - * the low order bits of a double precision number may - * not be adequately random, and may vary due to arithmetic - * implementation details on different computers. - * - * The other compile options generate an additional random - * integer that overwrites the low order bits of the double - * precision number. This reduces the period by a factor of - * two but tends to overcome the problems mentioned. - * - */ - - - -#include "mconf.h" - - -/* Three-generator random number algorithm - * of Brian Wichmann and David Hill - * BYTE magazine, March, 1987 pp 127-8 - * - * The period, given by them, is (p-1)(q-1)(r-1)/4 = 6.95e12. - */ - -static int sx = 1; -static int sy = 10000; -static int sz = 3000; - -static union { - double d; - unsigned short s[4]; -} unkans; - -/* This function implements the three - * congruential generators. - */ - -int ranwh() -{ -int r, s; - -/* sx = sx * 171 mod 30269 */ -r = sx/177; -s = sx - 177 * r; -sx = 171 * s - 2 * r; -if( sx < 0 ) - sx += 30269; - - -/* sy = sy * 172 mod 30307 */ -r = sy/176; -s = sy - 176 * r; -sy = 172 * s - 35 * r; -if( sy < 0 ) - sy += 30307; - -/* sz = 170 * sz mod 30323 */ -r = sz/178; -s = sz - 178 * r; -sz = 170 * s - 63 * r; -if( sz < 0 ) - sz += 30323; -/* The results are in static sx, sy, sz. */ -return 0; -} - -/* drand.c - * - * Random double precision floating point number between 1 and 2. - * - * C callable: - * drand( &x ); - */ - -int drand( a ) -double *a; -{ -unsigned short r; -#ifdef DEC -unsigned short s, t; -#endif - -/* This algorithm of Wichmann and Hill computes a floating point - * result: - */ -ranwh(); -unkans.d = sx/30269.0 + sy/30307.0 + sz/30323.0; -r = unkans.d; -unkans.d -= r; -unkans.d += 1.0; - -/* if UNK option, do nothing further. - * Otherwise, make a random 16 bit integer - * to overwrite the least significant word - * of unkans. - */ -#ifdef UNK -/* do nothing */ -#else -ranwh(); -r = sx * sy + sz; -#endif - -#ifdef DEC -/* To make the numbers as similar as possible - * in all arithmetics, the random integer has - * to be inserted 3 bits higher up in a DEC number. - * An alternative would be put it 3 bits lower down - * in all the other number types. - */ -s = unkans.s[2]; -t = s & 07; /* save these bits to put in at the bottom */ -s &= 0177770; -s |= (r >> 13) & 07; -unkans.s[2] = s; -t |= r << 3; -unkans.s[3] = t; -#endif - -#ifdef IBMPC -unkans.s[0] = r; -#endif - -#ifdef MIEEE -unkans.s[3] = r; -#endif - -*a = unkans.d; -return 0; -} |