Missing ldiv! overload on sparse QR

[ChrisRackauckas]

using SparseArrays, LinearAlgebra
A = rand(4,4)
S = sprand(4,4,0.1)
b = rand(4)
Aqr = qr(A)
Sqr = qr(S)
Aqr \ b # works!
Sqr \ b # works!
ldiv!(x, Aqr, b) # works!
ldiv!(x, Sqr, b) # fails!!!!!!!!!!!!!

[SobhanMP]

is this even supported in SPQR? i couldn't find anything in the user doc

[rayegun]

I will have to dig deeper into what SPQR is doing, I'm only really familiar with the UMFPACK and KLU code.

[rayegun]

SPQR does not support ldiv! natively. What do you want ldiv! to do @ChrisRackauckas? We can define a copying form, that copies to x.

[ViralBShah]

It should just give an error saying that the operation is not available, since you can't t do these things in-place.

[rayegun]

There's a MethodError now, do you think it should be more specific?

[ViralBShah]

Yes, I think an error message might make sense, since MethodError makes people think it is an unimplemented case.