add numerical recipes library

lib/nr/k_and_r/recipes/sobseq.c

@@ -0,0 +1,53 @@
+
+#include "nrutil.h"
+#define MAXBIT 30
+#define MAXDIM 6
+
+void sobseq(n,x)
+float x[];
+int *n;
+{
+	int j,k,l;
+	unsigned long i,im,ipp;
+	static float fac;
+	static unsigned long in,ix[MAXDIM+1],*iu[MAXBIT+1];
+	static unsigned long mdeg[MAXDIM+1]={0,1,2,3,3,4,4};
+	static unsigned long ip[MAXDIM+1]={0,0,1,1,2,1,4};
+	static unsigned long iv[MAXDIM*MAXBIT+1]={
+		0,1,1,1,1,1,1,3,1,3,3,1,1,5,7,7,3,3,5,15,11,5,15,13,9};
+
+	if (*n < 0) {
+		for (k=1;k<=MAXDIM;k++) ix[k]=0;
+		in=0;
+		if (iv[1] != 1) return;
+		fac=1.0/(1L << MAXBIT);
+		for (j=1,k=0;j<=MAXBIT;j++,k+=MAXDIM) iu[j] = &iv[k];
+		for (k=1;k<=MAXDIM;k++) {
+			for (j=1;j<=mdeg[k];j++) iu[j][k] <<= (MAXBIT-j);
+			for (j=mdeg[k]+1;j<=MAXBIT;j++) {
+				ipp=ip[k];
+				i=iu[j-mdeg[k]][k];
+				i ^= (i >> mdeg[k]);
+				for (l=mdeg[k]-1;l>=1;l--) {
+					if (ipp & 1) i ^= iu[j-l][k];
+					ipp >>= 1;
+				}
+				iu[j][k]=i;
+			}
+		}
+	} else {
+		im=in++;
+		for (j=1;j<=MAXBIT;j++) {
+			if (!(im & 1)) break;
+			im >>= 1;
+		}
+		if (j > MAXBIT) nrerror("MAXBIT too small in sobseq");
+		im=(j-1)*MAXDIM;
+		for (k=1;k<=IMIN(*n,MAXDIM);k++) {
+			ix[k] ^= iv[im+k];
+			x[k]=ix[k]*fac;
+		}
+	}
+}
+#undef MAXBIT
+#undef MAXDIM