i have this equation to use in ENVI 4.8. I do not have access to IDL so i cannot do it by using that. what i am wondering is if it possible to run the equation through Band Math. I am having more trouble with the integration equation (4). which i need to do to do equation (2) [url]https://picasaweb.google.com/lh/photo/QW9ihUPpzprEpq6A8VnOIA?feat=directlink[/url] thanks Rod