63 lines
1.3 KiB
C
63 lines
1.3 KiB
C
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/* Driver for routine polint */
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#include <stdio.h>
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#include <math.h>
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#define NRANSI
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#include "nr.h"
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#include "nrutil.h"
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#define PI 3.1415926
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int main(void)
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{
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int i,n,nfunc;
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float dy,f,x,y,*xa,*ya;
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printf("generation of interpolation tables\n");
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printf(" ... sin(x) 0<x<PI\n");
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printf(" ... exp(x) 0<x<1 \n");
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printf("how many entries go in these tables?\n");
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if (scanf("%d",&n) == EOF) return 1;
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xa=vector(1,n);
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ya=vector(1,n);
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for (nfunc=1;nfunc<=2;nfunc++) {
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if (nfunc == 1) {
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printf("\nsine function from 0 to PI\n");
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for (i=1;i<=n;i++) {
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xa[i]=i*PI/n;
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ya[i]=sin(xa[i]);
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}
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} else if (nfunc == 2) {
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printf("\nexponential function from 0 to 1\n");
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for (i=1;i<=n;i++) {
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xa[i]=i*1.0/n;
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ya[i]=exp(xa[i]);
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}
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} else {
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break;
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}
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printf("\n%9s %13s %16s %13s\n",
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"x","f(x)","interpolated","error");
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for (i=1;i<=10;i++) {
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if (nfunc == 1) {
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x=(-0.05+i/10.0)*PI;
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f=sin(x);
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} else if (nfunc == 2) {
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x=(-0.05+i/10.0);
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f=exp(x);
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}
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polint(xa,ya,n,x,&y,&dy);
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printf("%12.6f %12.6f %12.6f %4s %11f\n",
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x,f,y," ",dy);
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}
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printf("\n***********************************\n");
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printf("press RETURN\n");
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(void) getchar();
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}
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free_vector(ya,1,n);
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free_vector(xa,1,n);
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return 0;
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}
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#undef NRANSI
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