Good evening!

I am trying a simple matrix multiplication, however there is an element missing form the answer. This is how I prepare for the multiplication:

```
set lang aql;
CREATE ARRAY A<val:double> [row=0:1,2,0, col=0:2,3,0];
CREATE ARRAY B<val:double> [row=0:1,2,0, col=0:2,3,0];
INSERT INTO A '[[(0) (1) (2)] [(2) (3) (4)]]';
INSERT INTO B '[[(1) (0) (0)] [(2) (-3) (1)]]';
set lang afl;
load_library('linear_algebra');
load_library('dense_linear_algebra');
```

Then, when I run the matrix multiplication, the position {0,0} is missing from the answer

```
spgemm(A, transpose(B));
{row,row2} multiply
{0,1} -1
{1,0} 2
{1,1} -1
```

Am I doing something wrong?

Thanks!