#include <stdio.h>

void dprint( char *fmt, ...);
void dputchar( int c);

/*
 * plot() tabulates and plots n points of y vs. x
 * hplot() is like plot(), but histogram style
 * plot2d() plots without tabulating
 *
 * If x == NULL, 1..n is used for x
 */

#define SIZE 51		/* horizontal size for plot() and hplot() */

#define STAR	'*'	/* plotting characters */
#define SPACE	' '
#define VERT	'|'
#define DASH	'-'
#define CROSS	'+'

#define MIN(a,b)  ( (a) < (b) ? (a) : (b) )
#define MAX(a,b)  ( (a) > (b) ? (a) : (b) )


void hplot( char *title, double x[], double y[], int n)
{
    double ymin, ymax;		/* min/max values of y */
    double scale;		/* scale factor relating y values */
				/*  to number of stars printed */
    int i2;			/* number of STAR's to print */
    int i, j;			/* dummies */
/*
 * find ymin, ymax, and scale factor
 */
    ymin = y[0];
    ymax = y[0];

    for( j = 1; j < n; j++) {
	ymin = MIN( ymin, y[j]);
	ymax = MAX( ymax, y[j]);
    }

    scale = (ymax-ymin) / (SIZE-1);

    if( scale == 0.0)
	scale = 1.0;		/* prevent divide by zero later */
/*
 * print table & plot
 *
 */
    if( title)
	dprint("%28c%s\n", SPACE, title);

    for( j = 0; j < n; j++) {

	i2 = (y[j]-ymin) / scale + 1.5;	/* round to nearest point */

	dprint( "%12.5g  %12.5g  ", x ? x[j] : (double)(j+1), y[j]);

	for( i = 1; i <= i2; i++)
	    dputchar(STAR);

	dputchar('\n');
    }
}


void plot( char *title, double x[], double y[], int n)
{
    double ymin, ymax;		/* min/max values of y */
    double scale;		/* scale factor relating y values */
				/*  to number of stars printed */

    int i1, i2, k1, k2;		/* used in plotting section */

    int i, j;			/* dummies */
/*
 * find ymin, ymax, and scale factor
 */
    ymin = y[0];
    ymax = y[0];

    for( j = 1; j < n; j++) {
	ymin = MIN( ymin, y[j]);
	ymax = MAX( ymax, y[j]);
    }

    scale = (ymax-ymin) / (SIZE-1);

    if( scale == 0.0)
	scale = 1.0;		/* prevent divide by zero later */
/*
 * print table & plot
 *
 * i1 represents the position of the previous point, i2 the current point.
 * k1 & k2 are determined to print stars to connect the points.
 */
    if( title)
	dprint("%28c%s\n", SPACE, title);

    i1 = (y[0]-ymin) / scale + 1.5;	/* initial point */

    for( j = 0; j < n; j++) {

	i2 = (y[j]-ymin) / scale + 1.5;	/* round to nearest point */

	if( i2 >= i1) {
	    k1 = i1;
	    k2 = i2;
	} else {
	    k1 = i2;
	    k2 = i1;
	}

	dprint( "%12.5g  %12.5g  ", x ? x[j] : (double)(j+1), y[j]);

	for( i = 1; i < k1; i++)
	    dputchar(SPACE);

	for( i = k1; i <= k2; i++)
	    dputchar(STAR);

	dputchar('\n');

	i1 = i2;
    }
}


void plot2d(
	char *title,			/* string title for the plot */
	double x[], double y[],		/* arrays to plot */
	int n)				/* number of points used in x & y */
{
    double xmin, xmax, xscale; 	/* x & y min/max values */
    double ymin, ymax, yscale; 	/*  and scale factors */
	
    double xlabel[5], ylabel[5];/* numeric labels for x & y axes */
    double dx, dy;		/* delta x & y */

    char points[21][62];	/* character array to contain the plot */

    int row, col, i, m;		/* dummies */

					/* find min, max, and scales */
	if( x) {
	    xmin = x[0];
	    xmax = x[0];
	    for( i = 1; i < n; i++) {
		xmin = MIN( xmin, x[i] );
		xmax = MAX( xmax, x[i] );
	    }
	} else {
	    xmin = 1;
	    xmax = n;
	}
	
	ymin = y[0];
	ymax = y[0];

	for( i = 1; i < n; i++) {
	  ymin = MIN( ymin, y[i] );
	  ymax = MAX( ymax, y[i] );
	}
	
	dx = xmax - xmin;
	xscale = dx / 60.0;
	if( xscale == 0.0)
	    xscale = 1.0;	/* prevent divide by zero later */
	
	dy = ymax - ymin;
	yscale = dy / 20.0;
	if( yscale == 0.0)
	    yscale = 1.0;
/*
 * initialize labels and points
 */
	for( i = 0; i < 5; i++) {
	 xlabel[i] = xmin + i * dx / 4.0;
	 ylabel[i] = ymin + i * dy / 4.0;
	}
	
	for( row = 0; row < 21; row++)
	  points[row][61] = '\0';		/* terminate the strings */

	for( row = 0; row < 21; row++)
	 for( col = 0; col < 61; col++)
	  points[row][col] = SPACE;		/* all blanks to start with */

	for( row = 0; row < 21; row++)		/* make a grid with */
	 for( col = 0; col < 61; col += 15)
	  points[row][col] = VERT;	      /*  vertical line every 15 cols */
	
	for( row = 0; row < 21; row += 5)
	 for( col = 0; col < 61; col++)
	  points[row][col] = DASH;		/*  dash every 5 rows */

	for( row = 0; row < 21; row += 5)
	 for( col = 0; col < 61; col += 15)
	  points[row][col] = CROSS;		/*  cross at intersection */
	
	for( i = 0; i < n; i++)	{		/* plot the points */
	 row = (y[i]-ymin) / yscale + 0.5;
	 col = ((x ? x[i] : i+1) - xmin) / xscale + 0.5;
	 points[row][col] = STAR;
	}
	
	if( title)
	    dprint( "%12c%s\n", SPACE, title);

	m = 5;	/* for ylabel index */

	for( row = 20; row >= 0; row--) {

	  if( row % 5 == 0) { /* print ylabel */
	    m--;
	    dprint( "%12.5g%s\n", ylabel[m], points[row]);
	  } else
	    dprint( "%12c%s\n", SPACE, points[row]);
	}
	
	dprint( "%2c", SPACE);

	for( i = 0; i < 5; i++)
	    dprint( "%3c%12.5g", SPACE, xlabel[i]);

	dputchar('\n');
}