1 files changed, 89 insertions, 0 deletions
diff --git a/main_1.c b/main_1.c
new file mode 100644
index 0000000..cd84b67
--- /dev/null
+++ b/main_1.c
@@ -0,0 +1,89 @@
+#include <stdio.h>
+
+#if defined(PROG_SINUS_SUM)
+
+#define EPSILON	0.001*0.001
+#define MAX_ITERATIONS 100
+
+int main(void) {
+	puts("defined macro PROG_SINUS_SUM");
+	double x;
+	double result;
+	double last_elem;
+	int i;
+	
+	printf("Input a number\n");
+	scanf("%lf", &x);
+	last_elem = result = x;
+
+	for (i = 1; i < MAX_ITERATIONS; ++i) {
+		last_elem = last_elem * x * x / (2*i * (2*i+1));
+		if (last_elem*last_elem <= EPSILON) break;
+		result += last_elem * ( (i%2 * -2) + 1 );
+	}
+	printf("result = %lf; iterations = %i; last_elem = %lf\n", result, i, last_elem);
+	return 0;
+}
+
+#elif defined(PROG_MONTE_CARLO)
+
+#include <stdlib.h>
+#include <time.h>
+
+#define _USE_MATH_DEFINES
+#include <math.h>
+
+struct point {
+	float x, y;
+};
+
+struct circle {
+	// center not needed for this task
+	/*struct point center;*/
+	float rad;
+};
+
+char in_circle(const struct circle *c, const struct point p) {
+	/*p.x -= c->x;*/
+	/*p.y -= c->y;*/
+	return p.x * p.x + p.y * p.y < c->rad*c->rad;
+}
+
+float calculate_pi(int iterations) {
+	int in = 0, out = 0;
+	int *arr[2] = {&out, &in};
+	const struct circle c = {.rad = 1.0f};
+	for (int i = 0; i < iterations; ++i) {
+		struct point p = {
+			.x = rand() % 2000000u / 1e6f - 1,
+			.y = rand() % 2000000u / 1e6f - 1
+		};
+		++*arr[in_circle(&c, p)];
+	}
+	return (float)in/iterations * 4;
+}
+
+int main(int argc, char *argv[]) {
+	puts("defined macro PROG_MONTE_CARLO");
+	srand(time(NULL));
+	int iters;
+	if (argc == 2) {
+		iters = atoi(argv[1]);
+	} else {
+		fputs("Iterations: ", stdout);
+		if (!scanf("%i", &iters)) {
+			fputs("Input a valid number\n", stderr);
+			return EXIT_FAILURE;
+		}
+	}
+	float pi = calculate_pi(iters);
+	float err = fabs(M_PI-pi)/M_PI;
+	printf(	"calculated pi: %.4f, actual pi: %.4f\n"
+		"error: %.2f%%\n",
+		pi, M_PI, err * 100);
+	return EXIT_SUCCESS;
+}
+
+#else
+	#error "define macro PROG_SINUS_SUM or PROG_MONTE_CARLO in compilation flags"
+#endif