\n";
print "![](imagemap.php?mode=pic&formula=")
\n";
print "Enter a formula:
\n";
print "
\n";
print "The graph of $formula from 0 to $WIDTH
\n";
# print the imagemap
print "";
}
else # draw the picture
{
header("Content-Type: image/png");
$image = ImageCreate($WIDTH, $HEIGHT); # Make an image
$yellow = ImageColorAllocate($image, 255,255,0); # Allocate a color
$red = ImageColorAllocate($image, 255,0,0);
# Draw the background in yellow
ImageFilledRectangle($image, 0,0,$SIZEX, $SIZEY, $yellow);
$polygon = points($formula, 0, $WIDTH);
#print_r($polygon);
ImageFilledPolygon($image, $polygon, ($WIDTH + 1), $red);
ImagePNG($image);
}
function points($formula, $minx, $maxx)
{
# Make a polygon with the formula
$polygon[] = $maxx; # upper right corner
$polygon[] = 0;
$polygon[] = 0; # upper left corner
$polygon[] = 0;
for($x = $minx; $x < $maxx; $x++)
{
#print "\$x = $x; return $formula;
\n";
$y = round(eval("\$x = $x; return $formula;"));
$polygon[]=$x;
$polygon[]=$y;
}
return $polygon;
}
?>