add numerical recipes library

lib/nr/ansi/examples/xqrsolv.c

@@ -0,0 +1,75 @@
+
+/* Driver for routine qrdcmp */
+
+#include <stdio.h>
+#include <stdlib.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define NP 20
+#define MAXSTR 80
+
+int main(void)
+{
+	int j,k,l,m,n,sing;
+	float *x,**a,**ai,**b,*c,*d;
+	char dummy[MAXSTR];
+	FILE *fp;
+
+	x=vector(1,NP);
+	a=matrix(1,NP,1,NP);
+	b=matrix(1,NP,1,NP);
+	ai=matrix(1,NP,1,NP);
+	c=vector(1,NP);
+	d=vector(1,NP);
+	if ((fp = fopen("matrx1.dat","r")) == NULL)
+		nrerror("Data file matrx1.dat not found\n");
+	while (!feof(fp)) {
+		fgets(dummy,MAXSTR,fp);
+		fgets(dummy,MAXSTR,fp);
+		fscanf(fp,"%d %d ",&n,&m);
+		fgets(dummy,MAXSTR,fp);
+		for (k=1;k<=n;k++)
+			for (l=1;l<=n;l++) fscanf(fp,"%f ",&a[k][l]);
+		fgets(dummy,MAXSTR,fp);
+		for (l=1;l<=m;l++)
+			for (k=1;k<=n;k++) fscanf(fp,"%f ",&b[k][l]);
+		/* Save matrix a for later testing */
+		for (l=1;l<=n;l++)
+			for (k=1;k<=n;k++) ai[k][l]=a[k][l];
+		/* Do qr decomposition */
+		qrdcmp(a,n,c,d,&sing);
+		if (sing) fprintf(stderr,"Singularity in QR decomposition.\n");
+		/* Solve equations for each right-hand vector */
+		for (k=1;k<=m;k++) {
+			for (l=1;l<=n;l++) x[l]=b[l][k];
+			qrsolv(a,n,c,d,x);
+			/* Test results with original matrix */
+			printf("right-hand side vector:\n");
+			for (l=1;l<=n;l++)
+				printf("%12.6f",b[l][k]);
+			printf("\n%s%s\n","result of matrix applied",
+				" to sol'n vector");
+			for (l=1;l<=n;l++) {
+				b[l][k]=0.0;
+				for (j=1;j<=n;j++)
+					b[l][k] += (ai[l][j]*x[j]);
+			}
+			for (l=1;l<=n;l++)
+				printf("%12.6f",b[l][k]);
+			printf("\n*********************************\n");
+		}
+		printf("press RETURN for next problem:\n");
+		(void) getchar();
+	}
+	fclose(fp);
+	free_vector(d,1,NP);
+	free_vector(c,1,NP);
+	free_matrix(ai,1,NP,1,NP);
+	free_matrix(b,1,NP,1,NP);
+	free_matrix(a,1,NP,1,NP);
+	free_vector(x,1,NP);
+	return 0;
+}
+#undef NRANSI