plot contour for x y z without defining a function

I have some points with x y coordinates and value of stress of them saving in a matrix like z. how can i plot contour for these data? for example:

x=1 y=3 z=10
x=2.4 y=3.7 z=12
x=3.9 y=2.7 z=19
...

i cant write z as a function of x y because my equations are so complex and i just calculate results and want to contour for the results.

Thank You

Answer 1

[Walter Roberson]

See griddata() and see TriScatteredInterp()

The key is to use the existing data to interpolate a grid and then contour the grid.