Hi Robert, On your questions:

Why would you use meshgrid? Can you show us the code you are trying? It might be easier to see the problems that way.

My bad. I glanced through examples in the cookbook and thought that interpolate.bisplev needs to pass matrices rather than 1D arrays, which is not the case, hence was my confusion.

No, not really. You will not get sensible results if you try that.

You are right. Even though I do formally have a function defined on a line, this line does not have a structure, and thus I would not get sensible results in this way. I realized it after submitting the original question. My attempt to reformulate it as a line interpolation problem was due to my misinterpretation of the usage of function interpolate.bisplev per above. Looks like all I needed to do were these two standard lines of code: tck = interpolate.bisplrep(sValsOnReducedSet[:,0], sValsOnReducedSet[:,1], optValsOnReducedSet,s=0) optValsOnFullSet = interpolate.bisplev(sValsOnFullSet[:,0],sValsOnFullSet[:,1],tck) Thanks a lot for your help! Igor