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Re: Matrices-in-functions question


> Here is a simple one, but I can't work it out.
>
> I would like to be able to define a function this way:
>
> z=mat[[1]][[1]] a + mat[[1]][[2]]
>
> without specifying what "mat" is explicitly. I would evaluate it later
this
> way:
>
> z/.mat->somePredefinedMatrix
>
> Of course, Mathematica complains about the definition (Part specification
mat[[1]] is
> longer than depth of object) ... is there a way to make this fly?

I think this solves your problem:

z[mat_, a_] := mat[[1]][[1]] a + mat[[1]][[2]]

Use := rather than = to maintain the right hand side in unevaluated form
until the left hand side is actually used.

--
Stephen P Luttrell
Signal Processing and Imagery Department
DERA Malvern, St.Andrew's Road
Malvern, United Kingdom, WR14 3PS

+44 (0)1684 894046 (tel)
+44 (0)1684 894384 (fax)
luttrell at signal.dera.gov.uk (email)




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