Optimizing (Reducing run time) of a sparse matrix division

Hi, so I have a sparse matrix as shown below:
[ap ae 0 an 0 0 0 0 0 ...
[aw ap ae 0 an 0 0 0 0 ...
[0 aw ap 0 0 an 0 0 0 ...
[as 0 0 ap ae 0 an 0 0 0 ....
[0 as 0 aw ap ae 0 an 0 0 0 0 ...
and this matrix is multiplied by
[T1,1]
[T1,2]
[T1,3]
[T2,1]
T[2,2]
.
.
.
This is used to solve Ax=T
To find x, I use A\T,
but when the A matrix is really large (1000 x 1000 or even more), the matrix division starts taking up a lot of time, but most of the entries are 0.
I was wondering if there is any way to optimize this to reduce run time, or since it doesnt follow a particular pattern it can't be done?

6 件のコメント

Torsten
Torsten 2022 年 3 月 31 日
And you already work with A, T in sparse format ?
Steven Lord
Steven Lord 2022 年 3 月 31 日
What is "a lot of time" in this context?
Are aw, ap, ae, and/or T variables containing numbers or are they symbolic variables? If the latter, try substituting values for those variables before solving the system.
Walter Roberson
Walter Roberson 2022 年 3 月 31 日
If MATLAB is not able to detect one of the special sparse forms such as a bandwidth-limited matrix, then it uses solvers that typically end up needing dense matrices.
Bjorn Gustavsson
Bjorn Gustavsson 2022 年 4 月 1 日
If the standard methods doesn't "perform", then you can try the different iterative solvers available. You can check the documentation for Systems of Linear Equations for a list of those, or the help and documentation for pcg, bicg, bicgstab, bicgstabl, cgs, gmres, lsqr, minres, qmr, symmlq, or tfqmr.
Santosh Fatale
Santosh Fatale 2022 年 4 月 6 日
What is the sparsity of the first matrix (Matrix A) in your case?
What are the dimesion for matrix A and matrix T?
As pointed out Steven, are the variables in matrix A are of type syms?
If possible could you provide the data for matrix A and matrix T?
Walter Roberson
Walter Roberson 2022 年 4 月 6 日
sparse() matrices cannot hold symbolic variables.

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