These ExternalAttrib scripts estimate AVO intercept and gradient based on Shuey's 2 term approximation to the Zoeppritz equation.
Intercept and Gradient from 4 Angle Stacks
Takes as input 4 angle stacks and the corresponding angles and fits a least squares line to the amplitude and $ sin^2(angle) $ at each sample point. Ouput includes the intercept, gradient and the correlation coefficient of the line fit.
For each input volume the corresponding incident angle must be provided.