Initial data commit

Task/Euler-method/C/euler-method-1.c

@@ -0,0 +1,44 @@
+#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;
+}