I'm using polywarp and poly_2d to coregister a pair of 2-D images. I call polywarp to produce a linear fit and then call poly_2d. Using either nearest-neighbor or bilinear interpolation is fine - the results are good. Employing "cubic" interpolation with the cubic keyword set to -0.5 results in an IDL crash (Version: 7.0.3 Build id: 20080620). (A Visual Studio Just-in-Time Debugger window appears and then the IDL window containing "Fatal error: IDL has encountered a fatal error and will now exit.") The only difference between the poly_2d call that work and those that crash is the interpolation method. Does anyone have any suggestions wrt sinc interpolation using poly_2d?