51 lines
668 B
C
51 lines
668 B
C
#include "solve.h"
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#include <math.h>
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#include <float.h>
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int t9_solve (
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double (*f) (double),
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double a, double b,
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double eps, int m, double *x
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) {
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const double gdrt = 2 / (1 + sqrt(5));
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int it = 0;
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double x_1 = b + (a - b) * gdrt, x_2 = a + (b - a) * gdrt;
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double y_1 = f(x_1), y_2 = f(x_2);
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for (it = 1; it <= m; ++it)
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{
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if (y_1 - y_2 > DBL_EPSILON)
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{
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b = x_2;
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x_2 = x_1;
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y_2 = y_1;
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x_1 = b + (a - b) * gdrt;
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y_1 = f(x_1);
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} else
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{
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a = x_1;
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x_1 = x_2;
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y_1 = y_2;
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x_2 = a + (b - a) * gdrt;
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y_2 = f(x_2);
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}
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if (fabs(b - a) < eps)
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{
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*x = x_1;
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break;
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}
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}
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if (it > m)
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it = -1;
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return it;
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}
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