cholfact!
.. cholfact!(A [,LU=:U [,pivot=Val{false}]][;tol=1.0]) > Cholesky
``cholfact!`` is the same as :func:`cholfact`, but saves space by overwriting the input ``A``, instead of creating a copy. ``cholfact!`` can also reuse the symbolic factorization from a different matrix ``F`` with the same structure when used as: ``cholfact!(F::CholmodFactor, A)``.
Examples
The cholfact!
function in Julia performs a Cholesky factorization of a given matrix A
and overwrites the input matrix A
with the factorization result. It returns a Cholesky factorization object of size n x n
.
Here are some examples of how to use the cholfact!
function:

Perform Cholesky factorization and overwrite input matrix:
julia> A = [4.0 12.0 16.0; 12.0 37.0 43.0; 16.0 43.0 98.0]; julia> cholfact!(A) Cholesky{Float64,Array{Float64,2}} U factor: 3×3 UpperTriangular{Float64,Array{Float64,2}}: 2.0 6.0 8.0 ⋅ 1.0 5.0 ⋅ ⋅ 3.0
In this example, the
cholfact!
function performs a Cholesky factorization of the matrixA
and overwritesA
with the result. The returned object is a Cholesky factorization of the upper triangular matrix.  Reuse symbolic factorization from a different matrix:
julia> F = cholfact(A); julia> B = [1.0 2.0 3.0; 2.0 5.0 6.0; 3.0 6.0 9.0]; julia> cholfact!(F, B) Cholesky{Float64,Array{Float64,2}} U factor: 3×3 UpperTriangular{Float64,Array{Float64,2}}: 1.0 2.0 3.0 ⋅ 1.0 1.0 ⋅ ⋅ 0.0
This example demonstrates how to reuse the symbolic factorization from matrix
A
(stored inF
) and perform a Cholesky factorization of a different matrixB
. The input matrixB
is overwritten with the factorization result.
Note: The LU
and pivot
arguments mentioned in the documentation are optional parameters that control the factorization method. The tol
parameter specifies the tolerance level for rankdeficient factorizations.
See Also
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