I have been doing `A\b`

where `A`

is a sparse matrix. However, is there an in place version of `\`

? I have stumbled upon `A_ldiv_B!`

but it seems to me (1) this function has been deprecated and (2) it didn’t work on sparse matrices anyway.

I don’t think `A_ldiv_B!`

has been deprecated — you can still find this function in the latest master. (Maybe a specific method of it was deprecated?)

`A_ldiv_B!`

is supported for sparse matrices, but you have to give a factorization object, not the matrix itself. That is, if `A`

is a sparse matrix, then `F = factorize(A)`

to create the (sparse) LU (etc.) factorization, and then do `A_ldiv_B!(F, b)`

to solve Ax=b in-place in `b`

with the precomputed factorization.

Note that this is explained in the `A_ldiv_B!`

documentation: https://docs.julialang.org/en/latest/stdlib/linalg/#Base.LinAlg.A_ldiv_B!

**Update in 2019:** The corresponding function in Julia 1.0 or later is `ldiv!`

in the `LinearAlgebra`

standard library.

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