add numerical recipes library

lib/nr/ansi/recipes/ran1.c

@@ -0,0 +1,48 @@
+
+#define IA 16807
+#define IM 2147483647
+#define AM (1.0/IM)
+#define IQ 127773
+#define IR 2836
+#define NTAB 32
+#define NDIV (1+(IM-1)/NTAB)
+#define EPS 1.2e-7
+#define RNMX (1.0-EPS)
+
+float ran1(long *idum)
+{
+	int j;
+	long k;
+	static long iy=0;
+	static long iv[NTAB];
+	float temp;
+
+	if (*idum <= 0 || !iy) {
+		if (-(*idum) < 1) *idum=1;
+		else *idum = -(*idum);
+		for (j=NTAB+7;j>=0;j--) {
+			k=(*idum)/IQ;
+			*idum=IA*(*idum-k*IQ)-IR*k;
+			if (*idum < 0) *idum += IM;
+			if (j < NTAB) iv[j] = *idum;
+		}
+		iy=iv[0];
+	}
+	k=(*idum)/IQ;
+	*idum=IA*(*idum-k*IQ)-IR*k;
+	if (*idum < 0) *idum += IM;
+	j=iy/NDIV;
+	iy=iv[j];
+	iv[j] = *idum;
+	if ((temp=AM*iy) > RNMX) return RNMX;
+	else return temp;
+}
+#undef IA
+#undef IM
+#undef AM
+#undef IQ
+#undef IR
+#undef NTAB
+#undef NDIV
+#undef EPS
+#undef RNMX