Fri 07 Feb 2014 09:47:30 PM UTC, comment #9:
Oh no,
v = nonzeros(A .* B);
doesn't quite mean the same thing as
v = A(B)
since it ignores the zeros

Fri 07 Feb 2014 06:26:18 PM UTC, comment #8:
Well, that's definitely a clever work around. Good stuff.

Fri 07 Feb 2014 06:16:39 PM UTC, comment #7:
That is an entirely valid and reasonable request, however I'm afraid I can't ask my supervisor for money for this right now.
I do think I've found a workaround though (at least for numeric matrices).
To say A(B) = 0
I can instead use A = A  A .* B;
And to mean A(B) = C(B);
I can instead use A = A  A .* B + C .* B;
And for v = A(B), I can say v = nonzeros(A .* B);
And for A(B) = v, I can say
[i,j] = find(B);
[m,n] = size(B);
A = A  A .* B + sparse(i,j,v,m,n);

Fri 07 Feb 2014 05:05:46 PM UTC, comment #6:
Oh, right, stupid me.
There is no workaround other than looping through the i and j vectors.
You seem to really want this. Would you be able to tip me a little bit of money or ask your employer to do so if I spent a few hours or days trying to fix this about Octave? This problem doesn't affect me, and it doesn't affect most Octave users, and it would take a lot of effort to fix. Since you're the only person I know who is affected but you're apparently unable to fix Octave yourself, it would got a long way to motivate me to fix this if there was a little bit of money involved.
If not, you might wait until David Bateman tries to fix this. He might have other motivations to do so. Or perhaps another champion will arise from the shadows to squash this bug.

Fri 07 Feb 2014 04:21:04 PM UTC, comment #5:
That's not the same thing.
a(i,j) refers to all elements whose row is in the set i and whose column is in the set j.
But I only want the set of things whose (row,column) are among the set of pairs (i,j)

Fri 07 Feb 2014 02:31:46 PM UTC, comment #4:
A simple workaround is to use find:

Fri 07 Feb 2014 08:44:09 AM UTC, comment #3:
Can someone take another look at this? It's really driving me nuts. Is there a workaround I can use?

Tue 22 Oct 2013 06:27:27 PM UTC, comment #2:
This one is documented in the projects file
http://wiki.octave.org/Projects#Sparse_Matrices
What is happening now in your case is that the logical "b" is being converted to a single argument numeric index for the "true" values of the sparse logical matrix. This is identical to what happens for normal logical matrix indexing, but in the case of sparse matrices the values of the numerically index can depasse intmax().
The solution is the create a new idx_vector class particularly for sparse logical indexing that stores (row,column) pairs. If used in its default form it would act identically to idx_vector::idx_vector_rep, but the Sparse indexed assignment could then special case it.
There is no call to numel() anywhere here

Tue 22 Oct 2013 12:50:46 AM UTC, comment #1:
Ah, this is one that you won't be able to fix by avoiding calls to numel, Mr Bateman...

Mon 21 Oct 2013 11:08:04 PM UTC, original submission:
>> a = sprand(100000,100000,0.0001);
>> b = logical(sprand(100000,100000,0.0001));
>> a(b) = 0;
error: out of memory or dimension too large for Octave's index type
Note:
This bug also occurs in 3.6.4
