volume integral with discrete data points

Hello,

Could you please help me on how to calculate the volume (triple) integral of f(x,y,z) over x, y, z ? I know the range of the variables x, y, and z, as well as the values of f(x,y,z) for each x, y and z, but not the closed form mathematical expression of f(x,y,z). I was thinking of using 'trapz', but I can't figure out how it can be applied for volume (triple) integration.

Thanks!

[Walter Roberson]

There is a new way to do this in R2012a: do you have that release?