#include <stdio.h>
#include <math.h>
double fct_xp(double, double);
double fct_yp(double, double);
double b_g(double);
double g_b(double);
void polar(double, double, double*, double*);
void kartesisch(double, double, double*, double*);
void main()
{
	double xp, yp, r, phi;
	int eingabe = 0;
	do
	{
		printf("\n============================================================\
			   \nHauptmenue\n1 = Polarkoordinaten in kartesische Koordinaten\n2 = Kartesische Koordinaten \
			   in Polarkoordinaten\nEnde=99\n ---------------------------------------------------------------\n\n");
		scanf_s("%d", &eingabe);
		fflush(stdin);
		switch (eingabe)
		{
		case 1:
			printf("\nr eingeben: ");
			scanf_s("%lf", &r);
			fflush(stdin);
			printf("\nphi (Grad) eingeben: ");
			scanf_s("%lf", &phi);
			fflush(stdin);
			printf("\n-------------------------\n");
			kartesisch(r, phi, &xp, &yp);
			printf("xp = %lf\n", xp);
			printf("yp = %lf\n", yp); 
			break;
		case 2:
			printf("\nxp eingeben: ");
			scanf_s("%lf", &xp);
			fflush(stdin);
			printf("\nyp eingeben: ");
			scanf_s("%lf", &yp);
			fflush(stdin);
			printf("\n-------------------------\n");
			polar(xp, yp, &r, &phi);
			printf("r = %lf\n", r);
			printf("phi (Grad) = %lf\n", phi);
			break;
		default:
			break;
		}
	} while (eingabe != 99);
	return;
}
void polar(double xp, double yp, double *r, double *phi)
{
	*r = sqrt((xp*xp) + (yp*yp));
	*phi = b_g(atan2(yp,xp));
}

void kartesisch(double r, double phi, double *xp, double *yp)
{
	*xp = r * cos(g_b(phi));
	*yp = r * sin(g_b(phi));
}
double b_g(double argwinkel)
{
	double t = 0;
	t = (360 * argwinkel) / (2 * 3.14159);
	return t;
}
double g_b(double argwinkel)
{
	double t = 0;
	t = ((2 * 3.14159 * argwinkel) / 360);
	return t;
}