check arguments to sqrt() (from jerry@opal)

[unix-history] / usr / src / lib / libplot / dumb / subr.c

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/

#ifndef lint
static char sccsid[] = "@(#)subr.c      5.1 (Berkeley) %G%";
#endif not lint

#include "dumb.h"

/* Does not plot first point -- assumed that it is already plotted */
dda_line(ch, x0, y0, x1, y1)
       char ch;
       int x0, y0;     /* already transformed to screen coords */
       int x1, y1;     /* untransformed */
{
       int length, i;
       double deltaX, deltaY;
       double x, y;
       double floor();
       int abs();

       scale(x1, y1);

       length = abs(x1 - x0);
       if (abs(y1 -y0) > length)
               length = abs(y1 - y0);

       if (length == 0)
               return;

       deltaX = (double) (x1 - x0)/(double) length;
       deltaY = (double) (y1 - y0)/(double) length;

       x = (double) x0 + 0.5;
       y = (double) y0 + 0.5;

       for (i=0; i < length; ++i) {
               x += deltaX;
               y += deltaY;
               x0 = floor(x);
               y0 = floor(y);
               currentx = x0;
               currenty = y0;
               screenmat[currentx][currenty] = ch;
       }
}