59 lines
1.3 KiB
C
59 lines
1.3 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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double int_leftrect(double from, double to, double n, double (*func)())
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{
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double h = (to-from)/n;
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double sum = 0.0, x;
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for(x=from; x <= (to-h); x += h)
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sum += func(x);
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return h*sum;
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}
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double int_rightrect(double from, double to, double n, double (*func)())
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{
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double h = (to-from)/n;
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double sum = 0.0, x;
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for(x=from; x <= (to-h); x += h)
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sum += func(x+h);
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return h*sum;
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}
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double int_midrect(double from, double to, double n, double (*func)())
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{
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double h = (to-from)/n;
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double sum = 0.0, x;
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for(x=from; x <= (to-h); x += h)
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sum += func(x+h/2.0);
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return h*sum;
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}
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double int_trapezium(double from, double to, double n, double (*func)())
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{
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double h = (to - from) / n;
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double sum = func(from) + func(to);
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int i;
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for(i = 1;i < n;i++)
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sum += 2.0*func(from + i * h);
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return h * sum / 2.0;
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}
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double int_simpson(double from, double to, double n, double (*func)())
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{
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double h = (to - from) / n;
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double sum1 = 0.0;
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double sum2 = 0.0;
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int i;
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double x;
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for(i = 0;i < n;i++)
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sum1 += func(from + h * i + h / 2.0);
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for(i = 1;i < n;i++)
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sum2 += func(from + h * i);
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return h / 6.0 * (func(from) + func(to) + 4.0 * sum1 + 2.0 * sum2);
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}
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