matlisp-users

[Matlisp-users] Need help w/ computing sums

[Richard J. P. G. <rg...@bi...>]

Is there a good way to compute the following for a large matrix?

(v's are column vectors of V, u's are vectors of U)

I need the value of each line; I'm sort of dragging one matrix over
the other (horizontally) and adding the elements of the parts that
touch.

[v3] + [u1]

[v2 v3] + [u1 u2]

[v1 v2 v3] + [u1 u2 u3]

[v1 v2] + [u2 u3]

[v1] + [u3]

   

Re: [Matlisp-users] Need help w/ computing sums

[Tunc S. <si...@ro...>]

Hmm, that looks like a windowed fft. If that's the
case you may want to try (HELP FFT)

Richard James Panturis Giuly wrote:
> 
> Is there a good way to compute the following for a large matrix?
> 
> (v's are column vectors of V, u's are vectors of U)
> 
> I need the value of each line; I'm sort of dragging one matrix over
> the other (horizontally) and adding the elements of the parts that
> touch.
> 
> [v3] + [u1]
> 
> [v2 v3] + [u1 u2]
> 
> [v1 v2 v3] + [u1 u2 u3]
> 
> [v1 v2] + [u2 u3]
> 
> [v1] + [u3]
> 

I'm guessing that the intermediary results form another array of
length 2n-1.  I can't see any immediate way of doing this using
the higher level matlisp interfaces.  But you may be able to
do something clever with the direct interfaces.  Try (HELP BLAS)
and (HELP LAPACK).

Regards,
Tunc


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