iradon_speedy

This is a mex-accelerated implementation of iradon. It is a small modifidation to the standard iradon.m file, calling a mex-implemented routine that takes care of the most time-consuming part of the process, the backprojection. The C-code for the mex file is included, and is easily compiled at the Matlab command prompt using
>> mex Backproject.c
While iradon_speedy.m contains all the same options as the original iradon.m, the mex function is only used when iradon_speedy is called with either the nearest-neighbour or linear interpolation options (just because I didn't implement any of the other interpolation options).

Here is an example run:
>> f = phantom(256);
>> R = radon(f, 0:179);
>> f = iradon_speedy(R, 0:179, 'linear', 'Ram-Lak', 1, 256);

Simple as that. Speed-up factors range from 1.7 to 6.4, depending on the reconstruction scenario, and the compiler used.