66 lines
1.3 KiB
C
66 lines
1.3 KiB
C
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/* Driver for routine splint */
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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 NP 10
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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,nfunc;
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float f,x,y,yp1,ypn,*xa,*ya,*y2;
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xa=vector(1,NP);
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ya=vector(1,NP);
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y2=vector(1,NP);
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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<=NP;i++) {
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xa[i]=i*PI/NP;
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ya[i]=sin(xa[i]);
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}
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yp1=cos(xa[1]);
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ypn=cos(xa[NP]);
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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<=NP;i++) {
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xa[i]=1.0*i/NP;
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ya[i]=exp(xa[i]);
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}
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yp1=exp(xa[1]);
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ypn=exp(xa[NP]);
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} else {
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break;
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}
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/* Call spline to get second derivatives */
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spline(xa,ya,NP,yp1,ypn,y2);
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/* Call splint for interpolations */
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printf("\n%9s %13s %17s\n","x","f(x)","interpolation");
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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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splint(xa,ya,y2,NP,x,&y);
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printf("%12.6f %12.6f %12.6f\n",x,f,y);
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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(y2,1,NP);
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free_vector(ya,1,NP);
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free_vector(xa,1,NP);
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return 0;
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}
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#undef NRANSI
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