Description: ------------ When you use $AxisY->forceMinimum($ymin); you see the minimum value of y, the graph doesn't display any values of the user defined function less than the value request. However, if you use $AxisY->forceMaximum($ymax); the graph displayed apparently uses $ymax for the display, instead of just ignoring values greater than the $ymax given. Test script: --------------- You can view the script at: http://www.unitorganizer.com/download/vector.zip Call the script with a function using: vector.php?f=x^2&ymin=-10&ymax=10&xmin=-10&xmax=10 and try: vector.php?f=-x^2&ymin=-10&ymax=10&xmin=-10&xmax=10 Expected result: ---------------- You should see with the first example that the graph displays a vertical line at 10 for values of the function that are greater than 10, but with the 2nd example, the graph displays nothing for values of the graph less than -10.

Note that I meant horizontal line rather than vertical line.