Task

Multiply two matrices together.

They can be of any dimensions, so long as the number of columns of the first matrix is equal to the number of rows of the second matrix.




define matmul(a, b) -> c;
    lvars ba = boundslist(a), bb = boundslist(b);
    lvars i, i0 = ba(1), i1 = ba(2);
    lvars j, j0 = bb(1), j1 = bb(2);
    lvars k, k0 = bb(3), k1 = bb(4);
    if length(ba) /= 4 then
        throw([need_2d_array ^a])
    endif;
    if length(bb) /= 4 then
        throw([need_2d_array ^b])
    endif;
    if ba(3) /= j0 or ba(4) /= j1 then
        throw([dimensions_do_not_match ^a ^b]);
    endif;
    newarray([^i0 ^i1 ^k0 ^k1], 0) -> c;
    for i from i0 to i1 do
        for k from k0 to k1 do
            for j from j0 to j1 do
                c(i, k) + a(i, j)*b(j, k) -> c(i, k);
            endfor;
        endfor;
    endfor;
enddefine;