Free 3D Graph Software for Math Equations

[bomba923]

Do you guys know of any free online programs/calculators that can graph in 3D? Or, any site where I might download such a program?

In particular, I'm looking for a program that can graph
$$z = \int\limits_0^{2\pi } {\sqrt {1 + \left( {xy\cos xt} \right)^2 } dt}$$

(basic x,y,z coordinates)

 

[Hash]

Octave may be what you want

http://www.gnu.org/software/octave/

 

[neutrino]

Do you want to plot a graph or evaluate an integral? For the former you need a plotting software such as http://www.gnuplot.info/" , is used to solve integrals analytically, among many other things. Maxima doesn't plot on its own and therefore comes bundled along with gnuplot. Both softwares can be downloaded free of cost.

 

[Tide]

SciLab is also a very capable freebie: http://www.scilab.org/