Declaring a TF3 object

I have a file that has 4 columns. x,y,z and the last column has a value that is a function of x,y,z. Is there any way I can fill a TF3 object with this information ? I am sorry if I missed something obvious.

                                                           -thanks Debdatta.


Did you mean TH3 (an hisogram) in which case you would simply need to use TTree::Draw or did you mean a TF3 (a function object) in which case you simply need to write a wrapper C function that retrieve the value of x,y and z from the file and return the calculated value.