35 lines
553 B
C
35 lines
553 B
C
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#include <math.h>
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#define MAXIT 30
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float rtsec(float (*func)(float), float x1, float x2, float xacc)
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{
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void nrerror(char error_text[]);
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int j;
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float fl,f,dx,swap,xl,rts;
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fl=(*func)(x1);
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f=(*func)(x2);
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if (fabs(fl) < fabs(f)) {
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rts=x1;
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xl=x2;
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swap=fl;
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fl=f;
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f=swap;
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} else {
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xl=x1;
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rts=x2;
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}
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for (j=1;j<=MAXIT;j++) {
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dx=(xl-rts)*f/(f-fl);
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xl=rts;
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fl=f;
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rts += dx;
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f=(*func)(rts);
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if (fabs(dx) < xacc || f == 0.0) return rts;
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}
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nrerror("Maximum number of iterations exceeded in rtsec");
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return 0.0;
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}
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#undef MAXIT
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