Re: foo = eye (5); foo(1:3,:)(1:6) = 1

[Paul Kienzle]

On Mar 18, 2004, at 5:13 PM, Etienne Grossmann wrote:

> I was surprised to see that
>
>    foo = eye (5); foo(1:3,:)(1:6) = 1
>
>
>    error: in indexed assignment of matrix, last lhs index must be ()
>    error: assignment failed, or no method for `matrix = scalar'
>    error: evaluating assignment expression near line 32, column 32
>
> doesn't work w/ octave-2.1.53. Is that normal, or a bug?

I'm not surprised.  In fact I would be surprised if it had
worked.  I'm also pleased by the polite error message.

Not that I believe it should or should not work,  just that
the underlying array implementation uses dense arrays,
with no option to represent an array as a slice of another
array, so it would be tricky to map the assignment back
into the original array through two levels of subscripting.

The same construct, foo(1:3,:)(1:6), works as RHS because
foo(1:3,:) becomes a temporary octave value which then is
subscripted by (1:6).

BTW, doesn't foo(1:3,1:2)=1 give you what you want?

Paul Kienzle
address@hidden



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