add numerical recipes library

lib/nr/ansi/recipes/wwghts.c

@@ -0,0 +1,52 @@
+
+void wwghts(float wghts[], int n, float h,
+	void (*kermom)(double [], double ,int))
+{
+	int j,k;
+	double wold[5],wnew[5],w[5],hh,hi,c,fac,a,b;
+
+	hh=h;
+	hi=1.0/hh;
+	for (j=1;j<=n;j++) wghts[j]=0.0;
+	(*kermom)(wold,0.0,4);
+	if (n >= 4) {
+		b=0.0;
+		for (j=1;j<=n-3;j++) {
+			c=j-1;
+			a=b;
+			b=a+hh;
+			if (j == n-3) b=(n-1)*hh;
+			(*kermom)(wnew,b,4);
+			for (fac=1.0,k=1;k<=4;k++,fac*=hi)
+				w[k]=(wnew[k]-wold[k])*fac;
+			wghts[j] += (
+				((c+1.0)*(c+2.0)*(c+3.0)*w[1]
+				-(11.0+c*(12.0+c*3.0))*w[2]
+				+3.0*(c+2.0)*w[3]-w[4])/6.0);
+			wghts[j+1] += (
+				(-c*(c+2.0)*(c+3.0)*w[1]
+				+(6.0+c*(10.0+c*3.0))*w[2]
+				-(3.0*c+5.0)*w[3]+w[4])*0.5);
+			wghts[j+2] += (
+				(c*(c+1.0)*(c+3.0)*w[1]
+				-(3.0+c*(8.0+c*3.0))*w[2]
+				+(3.0*c+4.0)*w[3]-w[4])*0.5);
+			wghts[j+3] += (
+				(-c*(c+1.0)*(c+2.0)*w[1]
+				+(2.0+c*(6.0+c*3.0))*w[2]
+				-3.0*(c+1.0)*w[3]+w[4])/6.0);
+			for (k=1;k<=4;k++) wold[k]=wnew[k];
+		}
+	} else if (n == 3) {
+		(*kermom)(wnew,hh+hh,3);
+		w[1]=wnew[1]-wold[1];
+		w[2]=hi*(wnew[2]-wold[2]);
+		w[3]=hi*hi*(wnew[3]-wold[3]);
+		wghts[1]=w[1]-1.5*w[2]+0.5*w[3];
+		wghts[2]=2.0*w[2]-w[3];
+		wghts[3]=0.5*(w[3]-w[2]);
+	} else if (n == 2) {
+		(*kermom)(wnew,hh,2);
+		wghts[1]=wnew[1]-wold[1]-(wghts[2]=hi*(wnew[2]-wold[2]));
+	}
+}