4D interpolation

[Eric S Fraga]

Ben Abbott <bpabbott at mac.com> writes:
> On Jul 3, 2008, at 11:31 AM, Eric S Fraga <e.fraga at ucl.ac.uk> wrote:
>
>> I've been following the brief thread on interpolation with interest.
>> Very helpful.
>>
>> However, I have a problem in which I need to interpolate (2d only)
>> onto a surface that is not square.  Given interp2:
>>
>>     ZI = interp2 (X, Y, Z, XI, YI)
>>
>> I wish to interpolate (or maybe, if need be, approximate) Z to get ZI
>> where XI and YI are not the same size.  And neither are the original X
>> and Y for that matter.  interp2 does not allow this.  Can anybody
>> please suggest an alternative?
>>
>
> By not the same size I assume you are implying X & Y are vectors, and
> Z is a 2D array?
>
> If so check out meshgrid or ndgrid.
>
> Ben

By not the same size, I meant that size(XI) != size(YI).  Pointing me
to meshgrid was very helpful as it's made me realise that XI and YI
need to be matrices.  I had thought they could be vectors as X and Y
are.  Using meshgrid to create XI and YI (from my original vectors)
gives me what I need and interp2 does the job.

Many thanks for the pointer and for the very speedy response!

eric