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Euler method: Difference between revisions
→{{header|C}}
(→{{header|Common Lisp}}: Removed misleading, CL-specific output, since people seem to needlessly copy it to other languages-) |
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done
</pre>
=={{header|C}}==
<lang c>#include <stdio.h>
#include <math.h>
typedef double (*deriv_f)(double, double);
#define FMT " %7.3f"
void ivp_euler(deriv_f f, double y, int step, int end_t)
{
int t = 0;
printf(" Step %2d: ", (int)step);
do {
if (t % 10 == 0) printf(FMT, y);
y += step * f(t, y);
} while ((t += step) <= end_t);
printf("\n");
}
void analytic()
{
double t;
printf(" Time: ");
for (t = 0; t <= 100; t += 10) printf(" %7g", t);
printf("\nAnalytic: ");
for (t = 0; t <= 100; t += 10)
printf(FMT, 20 + 80 * exp(-0.07 * t));
printf("\n");
}
double cooling(double t, double temp)
{
return -0.07 * (temp - 20);
}
int main()
{
analytic();
ivp_euler(cooling, 100, 2, 100);
ivp_euler(cooling, 100, 5, 100);
ivp_euler(cooling, 100, 10, 100);
return 0;
}</lang>output<lang> Time: 0 10 20 30 40 50 60 70 80 90 100
Analytic: 100.000 59.727 39.728 29.797 24.865 22.416 21.200 20.596 20.296 20.147 20.073
Step 2: 100.000 57.634 37.704 28.328 23.918 21.843 20.867 20.408 20.192 20.090 20.042
Step 5: 100.000 53.800 34.280 26.034 22.549 21.077 20.455 20.192 20.081 20.034 20.014
Step 10: 100.000 44.000 27.200 22.160 20.648 20.194 20.058 20.017 20.005 20.002 20.000</lang>
=={{header|C++}}==
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