// Calculation Program for displaying an original egg-shaped-curve(Itou's), 06 (Thurs.) May., 2010

// in the case that a=0.5, b=0.37

// file name: C_program_3_E.c



#include< stdio.h>

#include< math.h>



void main(void)

{

	double x,y,a,b,pi;

	double t,dt;

	int i,imax;

	double xx[10001],yy[10001];// Take care of the upper limit of storage memory capacitance.



	FILE *fp;



// Setting of the constants

        pi=3.1415927;

        a=.5;

	b=.37;



	printf("a=%f\n\n",a);



// Setting of the other parameters

	dt=pi/2000;// plotting interval of t



	i=0;



// execution of calculation

	for(t=-2*pi;t<=2*pi;t=t+dt)

	{

		i++;



		x=a*cos(t);

		y=b*cos(t/4)*sin(t);

		xx[i]=x;

		yy[i]=y;



		printf("i=%d,x=%f,y=%f\n",i,x,y);

	}



	imax=i;



// writing the calculated coordinates data of the curve into a textfile

	fp=fopen("egg_shaped_curve.txt","w");



	if(fp==NULL)

	{

		printf("FILE OPEN ERROR\n");

	}

	else

	{

		for(i=1;i<=imax;i++)

		{

			fprintf(fp,"%f,%f\n",xx[i],yy[i]);

		}



	fflush(fp);

	fclose(fp);

	}



	printf("end\n");

}// the end of the program