/*********************************************************************
   For interactive terminal use. Produce a crude graph of the function
   fx over the prompted for interval x1, x2. Querey for another plot
   until user sginals satisfaction.
   C.A. Bertulani        May/21/2000
*********************************************************************/

typedef double Number;

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


int main(){
	void screen(Number (*)(Number));
	cout << "This is sin(x). Try something different.\n";
	Number fx(Number );
	screen(fx);	
	return 0;
}
/*********************************************************************
   Here is the fnction you want to plot.
   C.A. Bertulani        May/21/2000
*********************************************************************/
Number fx(Number x){
	return sin(x);
}
/*********************************************************************
   For interactive terminal use. Produce a crude graph of the function
   fx over the prompted for interval x1, x2. Querey for another plot
   until user sginals satisfaction.
   C.A. Bertulani        May/21/2000
*********************************************************************/
#define ISCR 60		/* Number of horizontal and vertical posstions in display */
#define JSCR 21
#define BLANK ' '
#define ZERO '-'
#define YY 'l'
#define XX '-'
#define FF 'x'

void screen(Number (*fx)(Number))
{
	int jz,j,i;
	Number ysml,ybig,x2,x1,x,dyj,dx,y[ISCR+1];
	char scr[ISCR+1][JSCR+1];

	for (;;) {
		cout << "Enter x1 x2 (x1=x2 to stop):\t"; /* Query for another plot, */
		cin >> x1 >> x2;							/* quit if x1 = x2 */
		if (x1 == x2) break;
		for (j=1;j<=JSCR;j++)			/* Fill vertical sides with character 'l' */
			scr[1][j]=scr[ISCR][j]=YY;
		for (i=2;i<=(ISCR-1);i++) {
			scr[i][1]=scr[i][JSCR]=XX;	/* Fill top, bottom with character '-' */	
			for (j=2;j<=(JSCR-1);j++)	/* Fill interior with blanks. */
				scr[i][j]=BLANK;
		}
		dx=(x2-x1)/(ISCR-1);
		x=x1;
		ysml=ybig=0.0;		/* Limits will include 0. */
		for (i=1;i<=ISCR;i++) {	/* Evaluate the fuction at equal intervals. */
			y[i]=(*fx)(x);		/* Find the largest and the smallest values. */
			if (y[i] < ysml) ysml=y[i];
			if (y[i] > ybig) ybig=y[i];
			x += dx;
		}
		if (ybig == ysml) ybig=ysml+1.0;	/* Be sure to separate top and bottom. */
		dyj=(JSCR-1)/(ybig-ysml);
		jz=1-(int) (ysml*dyj);		/* Note which row corresponds  to 0. */
		for (i=1;i<=ISCR;i++) {		/* Place an indicator at function height and 0. */
			scr[i][jz]=ZERO;
			j=1+(int) ((y[i]-ysml)*dyj);
			scr[i][j]=FF;
		}
		cout << setiosflags(ios::fixed);
		cout << setw(11) << setprecision(3) << ybig << " ";
		for (i=1;i<=ISCR;i++) cout << scr[i][JSCR];
		cout << "\n";
		for (j=(JSCR-1);j>=2;j--) {	/* Display. */
			cout << setw(12) << " ";
			for (i=1;i<=ISCR;i++) cout << scr[i][j];
			cout << "\n";
		}
		cout << setiosflags(ios::fixed);
		cout << setw(11) << setprecision(3) << ysml << " ";
		for (i=1;i<=ISCR;i++) cout << scr[i][1];
		cout <<"\n";
		cout << setiosflags(ios::fixed);
		cout<<setw(16) << setprecision (3) << x1 << setw(59) << setprecision (3) << x2 <<'\n';
	}
}
#undef ISCR
#undef JSCR
#undef BLANK
#undef ZERO
#undef YY
#undef XX
#undef FF
/*********************************************************************/