Given the following example is there a way to achieve bicubic interpolation without generating an entire finely-spaced grid?:
years = [5,10,20,25,40];
service = 1:3;
wage = [50 99 787.685
779 795 850
803 779 388
886 753 486
849 780 598];
w = interp2(service,years,wage,1.5,37.5,'cubic')
Warning: The 'cubic' method requires the grid to have a uniform spacing. Switching the method from 'cubic' to 'spline' because this condition is not met.
I understand the reason for the warning. So wish to find a solution by specifying particular points without having to generate an entire equally spaced surface (the data available is not equally spaced). Does not necessarily have to be interp2. I will have to run this for hundreds of surfaces and hundreds of query points so would need to be quite fast at returning "w". Any ideas?
If you insist on using 'cubic' interpolation method you can use griddata which is designated for interpolating scattered data, i.e. data which is not defined on uniform spaced grid:
years = [5,10,20,25,40];
service = 1:3;
wage = [50 99 787.685
779 795 850
803 779 388
886 753 486
849 780 598];
w = griddata(service,years,wage,1.5,37.5,'cubic')