I am afraid that ENVI does not provide tools for regression analysis. You could write a tool using IDL code, and add it to ENVI as a custom extension if you would like. - Peg

And from where can i find that so to add as an extension?

I am not sure exactly what your question means. Perhaps you are looking for information about how to add an extension to ENVI? If so, then you will probably want to take a look at the section in the ENVI Help called "Write and Deploy ENVI Toolbox Extensions". You can find that in the online Documentation Center at http://www.harrisgeospatial.com/docs/.... If you are wondering which IDL routines you will want to use in your extension code to perform regression, then there are different routines for different types of regression. You will probably want to consider the REGRESS routine. The documentation for this routine in our Documentation Center is at http://www.harrisgeospatial.com/docs/.... Of course, you can also find both of those sections of the ENVI and IDL documentation in the ENVI and IDL products themselves. Regards, Peg

I ll check through these. it might be helpful as im new to ENVI IDL.