// Calculation Program for displaying a single heart curve coversed from a Cardioid_2b_2; R=a(1-sin t), x=r cos t and y=r sin t. 26 Dec., 2011

// file name: heart_curve_2b_2.c

#include< stdio.h>
#include< math.h>

void main(void)
{
	double a,pi;// a is the constant of the original Cardioid, pi is the pi
	double r,f,df;// the moving radius, the phase angle [radian] and its increment [radian] of a Cardioid after a conversion respectively
	double t;// the phase angle [radian] before the conversion
	double fmin,fmax;// the minimum and maximum values of the phase angle "f" respectively
	double b,c;// coefficients of the conversion from a Cardioid to a heart curve
	double d;// the ratio of expansion and contraction in the vertical direction
	double k;// reduction coefficient from one piriod interval (2*pi) into reduced piriod one of the variable in sinusoidal function
	int i,imax;
	double xx[10001],yy[10001];// Take care of the upper limit of storage memory capacitance.

	FILE *fp;

// setting of the constant
	pi=3.14159265;
	a=1;

	b=1.35;// suitable at between 1.3 and 2.0
	c=0.7;// It must be in 0 < c <1 and is suitable at between 0.5 and 0.8.
	d=1.05;// suitable at between 0.7 and 1.5
	k=0.97;// 0 < k <= 1

// setting of the other parameters
	fmin=-pi/2;
	fmax=3*pi/2;
	df=(fmax-fmin)/4000;// plotting interval of the phase angle "f"

// execution of calculation
	i=0;
	for(f=fmin;f<= fmax;f=f+df)
		{
		i++;

		t=(1-b)*(f-pi/2)+2*b*asin((f-pi/2)*sin(pi*k/2)/pi)/k+pi/2;
		r=a*(1-sin(t));

		xx[i]=r*(1+c*sin(f))*cos(f);
		yy[i]=d*r*(1+c*sin(f))*sin(f);

		printf("i=%d,x=%f,y=%f\n",i,xx[i],yy[i]);
		}
	imax=i;

// writing the calculated coordinates data of the curve into a textfile
	fp=fopen("heart_curve_2b_2.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