Question: Erroneous 3D plot outcome.

Hi All.

I keep getting a incorrect plot of: plot3d(2*x/(x^2+y^2), x = -10 .. 10, y = -10 .. 10)

The negative range excursion is not appearing.

I have tried changing the domains and range settings but to no avail.

I have also tried placing brackets around the numerator and denominator but again to no avail. I also repeated the plot of earlier functions, on the same sheet, below the above function and had no problems with them. See the function below as an example of a good graph plot.

I noticed that the program flashes a negative value graph on screen and then only displays a positive result as shown above.

Good plot of: plot3d((-2*x^2+2*y^2)/(x^2+y^2)^2, x = -10 .. 10, y = -10 .. 10)

This example shows both the negative and positive f(x,y) values and surfaces.

Can anyone explain what is going on.

What I may be overlooking.

Is there a flaw in Maple 15?

I can get the correct graph using Microsoft Math which is a much less sophisticated program.

Omicron1