88 lines
2.0 KiB
C
88 lines
2.0 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include "nr.h"
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void dbessj0(float x, float *y, float *dy) {
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*y = bessj0(x);
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*dy = -bessj1(x);
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}
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int main() {
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/*
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1. using zbrak, find all possible intervals with roots.
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2. and use routines and enumerate all roots.
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*/
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float a = 1.0, b = 10.0;
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float xacc = 0.000001;
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int n = 23;
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float *xb1 = calloc(sizeof(float), n);
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float *xb2 = calloc(sizeof(float), n);
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int nb;
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int i;
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zbrak(bessj0, a, b, n, xb1, xb2, &nb);
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for (i = 1; i <= nb; i++) {
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printf("[%f, %f]\n", xb1[i], xb2[i]);
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}
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float *roots_bisect = calloc(sizeof(float), nb);
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float *roots_linter = calloc(sizeof(float), nb);
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float *roots_secant = calloc(sizeof(float), nb);
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float *roots_newt = calloc(sizeof(float), nb);
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float *roots_newtsafe = calloc(sizeof(float), nb);
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for (i = 0; i < nb; i++) {
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float l = xb1[i + 1];
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float r = xb2[i + 1];
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roots_bisect[i] = rtbis(bessj0, l, r, xacc);
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roots_linter[i] = rtflsp(bessj0, l, r, xacc);
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roots_secant[i] = rtsec(bessj0, l, r, xacc);
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roots_newt[i] = rtnewt(dbessj0, l, r, xacc);
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roots_newtsafe[i] = rtsafe(dbessj0, l, r, xacc);
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}
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printf("besection roots: ");
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for (i = 0; i < nb; i++) {
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printf("%f ", roots_bisect[i]);
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}
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printf("\n");
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printf("lin-interpoalation roots: ");
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for (i = 0; i < nb; i++) {
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printf("%f ", roots_linter[i]);
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}
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printf("\n");
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printf("secant roots: ");
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for (i = 0; i < nb; i++) {
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printf("%f ", roots_secant[i]);
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}
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printf("\n");
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printf("newton-raphson roots: ");
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for (i = 0; i < nb; i++) {
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printf("%f ", roots_newt[i]);
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}
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printf("\n");
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printf("newton with bracketing roots: ");
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for (i = 0; i < nb; i++) {
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printf("%f ", roots_newtsafe[i]);
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}
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printf("\n");
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/* free */
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free(xb1);
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free(xb2);
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free(roots_bisect);
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free(roots_linter);
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free(roots_secant);
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free(roots_newt);
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return 0;
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} |