jens
8867efa451
Committed on the Free edition of March Hare Software CVSNT Server. Upgrade to CVS Suite for more features and support: http://march-hare.com/cvsnt/ git-svn-id: http://moon:8086/svn/vhdl/trunk@272 cc03376c-175c-47c8-b038-4cd826a8556b
87 lines
1.7 KiB
C
87 lines
1.7 KiB
C
/* random.c
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Author: Numerical recipes (ran1, gaussian), Jon Hamkins (others)
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Revised by: Jon Hamkins
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Date: 4-16-98
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*/
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#include <math.h>
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#define IA 16807
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#define IM 2147483647
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#define AM (1.0/IM)
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#define IQ 127773
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#define IR 2836
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#define NTAB 32
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#define NDIV (1+(IM-1)/NTAB)
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#define EPS 1.2e-14
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#define RNMX (1.0-EPS)
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/* From Numerical Recipes, p. 280, modified from float to double */
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/* returns a uniform deviate in (0,1) */
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double ran1(long *idum)
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{
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int j;
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long k;
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static long iy=0;
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static long iv[NTAB];
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double temp;
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if (*idum <=0 || !iy) {
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if (-(*idum) < 1) *idum=1;
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else *idum = -(*idum);
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for (j=NTAB+7; j>=0; j--) {
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k=(*idum)/IQ;
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*idum=IA*(*idum-k*IQ)-IR*k;
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if (*idum < 0) *idum += IM;
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if (j < NTAB) iv[j] = *idum;
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}
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iy = iv[0];
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}
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k=(*idum)/IQ;
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*idum=IA*(*idum-k*IQ)-IR*k;
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if (*idum < 0) *idum += IM;
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j=iy/NDIV;
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iy=iv[j];
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iv[j] = *idum;
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if ((temp=AM*iy) > RNMX) return RNMX;
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else return temp;
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}
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#undef IA
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#undef IM
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#undef AM
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#undef IQ
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#undef IR
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#undef NTAB
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#undef NDIV
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#undef EPS
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#undef RNMX
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/* Generate a N(0,1) r.v. */
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double gaussian(long *idum)
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{
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static int iset=0;
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static double gset;
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double fac,r,v1,v2;
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double ran1();
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if (iset == 0) {
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do {
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v1=2.0*ran1(idum)-1.0;
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v2=2.0*ran1(idum)-1.0;
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r=v1*v1+v2*v2;
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} while (r >= 1.0 || r == 0.0);
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fac=sqrt(-2.0*log(r)/r);
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gset=v1*fac;
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iset=1;
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return v2*fac;
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} else {
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iset=0;
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return gset;
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}
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}
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/* generate a random bit */
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int random_bit(long *idum)
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{
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return((ran1(idum)<0.5) ? 0 : 1);
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}
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