I’d like to compute QR factorisation `Q, R = qr(A)`

followed by the operation `Matrix(Q)' * Y`

. As far as I can tell, `Matrix(Q)`

allocates another matrix the same size as `A`

which I’d like to avoid.

Is there a way to perform `Matrix(Q)' * Y`

that doesn’t allocate the matrix `Matrix(Q)`

? I can of course do `(Q' * Y)[1:Ncols]`

where `Ncols`

where `Ncols = size(A,2)`

, but if `Ncols << Nrows`

then I would prefer to avoid this if possible.