[Blitz-support] interpolation / sorting multidimensional arrays

[Jonathan S. <jjs...@my...>]

Hi

I am relatively new to Blitz++ (and c++ programming in general), but I 
am very impressed.  I have recently translated a good deal of my own 
Matlab code to c++ by using Blitz arrays.

I would like to interpolate within a set of data points given by 
one-dimensional arrays (e.g. x and y for 1D interpolation) to find a 
value at an arbitrary point within the range of the data.  Not being 
able to find an existing function to do this, I planned to write a 
simple linear interpolation function.  However, I am stuck at sorting 
the data points.  Essentially, I need to sort x from least to greatest 
and then reorder y so that there is 1-1 correspondence with the original 
data points.

I can sort x by:

sort( &x(0), &x(x.size())+1);

but I am at a loss at how to reorder y accordingly.  Other than writing 
a sorting function from scratch, the methods I can think of would be 
extremely inefficient (O(N^2)).  Does anyone have a suggestion?

Regards,
Jonathan