Re: octave "Most Wanted" feature

[Quentin Spencer]

Przemek Klosowski wrote:
>    >         > octave_index_origin (-256);
>
>    Er, no. There are two choices, 0 and 1. There are no other choices. 
>
> One interesting application of an offset that is neither 0 nor 1 is
> used for memory allocation in Numerical Recipes. For example, they
> allocate a 128-element vector and then subtract 128 from the
> allocation pointer 'v', to access v(129..256). Ugly hack, but it
> simplifies array offset expressions sometimes.
>   

Another example the output of the fftshift function, which moves the DC 
frequency to the middle of a vector. Using a negative index origin would 
make it possible for the index to correspond directly to the frequency.

Quentin