50 lines
1.1 KiB
C++
50 lines
1.1 KiB
C++
#include "nr.h"
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void NR::sobseq(const int n, Vec_O_DP &x)
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{
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const int MAXBIT=30,MAXDIM=6;
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int j,k,l;
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unsigned long i,im,ipp;
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static int mdeg[MAXDIM]={1,2,3,3,4,4};
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static unsigned long in;
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static Vec_ULNG ix(MAXDIM);
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static Vec_ULNG_p iu(MAXBIT);
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static unsigned long ip[MAXDIM]={0,1,1,2,1,4};
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static unsigned long iv[MAXDIM*MAXBIT]=
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{1,1,1,1,1,1,3,1,3,3,1,1,5,7,7,3,3,5,15,11,5,15,13,9};
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static DP fac;
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if (n < 0) {
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for (k=0;k<MAXDIM;k++) ix[k]=0;
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in=0;
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if (iv[0] != 1) return;
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fac=1.0/(1 << MAXBIT);
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for (j=0,k=0;j<MAXBIT;j++,k+=MAXDIM) iu[j] = &iv[k];
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for (k=0;k<MAXDIM;k++) {
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for (j=0;j<mdeg[k];j++) iu[j][k] <<= (MAXBIT-1-j);
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for (j=mdeg[k];j<MAXBIT;j++) {
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ipp=ip[k];
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i=iu[j-mdeg[k]][k];
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i ^= (i >> mdeg[k]);
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for (l=mdeg[k]-1;l>=1;l--) {
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if (ipp & 1) i ^= iu[j-l][k];
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ipp >>= 1;
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}
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iu[j][k]=i;
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}
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}
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} else {
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im=in++;
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for (j=0;j<MAXBIT;j++) {
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if (!(im & 1)) break;
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im >>= 1;
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}
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if (j >= MAXBIT) nrerror("MAXBIT too small in sobseq");
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im=j*MAXDIM;
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for (k=0;k<MIN(n,MAXDIM);k++) {
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ix[k] ^= iv[im+k];
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x[k]=ix[k]*fac;
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}
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}
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}
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