# Question:Where is the question about the pseudo inverse of a matrix

## Question:Where is the question about the pseudo inverse of a matrix

MaplePrimes

Not the first time that a question (OP's name  PhearunSeng ) is removed as I am writing an answer (I guess other people have already faced the same inconvenience).
Why doesn't exist a mechanism which prevents removing, deleting, displacing a question where someone (here Carl) has akready given an answer ???

Whatever the reason, here is my answer

Title: Can be done quickly if you write the matrix in a more abstract form

```MyKGff := Matrix(5, 5,
{
(1, 1) = A+(1/63368)*B,
(1, 2) = -(1/63368)*B,
(1, 3) = -(1/39605)*B,
(1, 4) = 0,
(1, 5) = 0,
(2, 1) = -(1/63368)*B,
(2, 2) = (1/63368)*B+C,
(2, 3) = (1/39605)*B,
(2, 4) = -C,
(2, 5) = 0,
(3, 1) = -(1/39605)*B,
(3, 2) = (1/39605)*B,
(3, 3) = (8/198025)*B,
(3, 4) = 0,
(3, 5) = 0,
(4, 1) = 0,
(4, 2) = -C,
(4, 3) = 0,
(4, 4) = C+(1/63368)*F,
(4, 5) = -(1/39605)*F,
(5, 1) = 0,
(5, 2) = 0,
(5, 3) = 0,
(5, 4) = -(1/39605)*F,
(5, 5) = (8/198025)*F
}
);
```

Then (Maple 2015.2)

```PseudoInverse := CodeTools:-Usage( LinearAlgebra:-MatrixInverse(MyKGff, method=pseudo) ):
memory used=28.38MiB, alloc change=68.00MiB, cpu time=312.00ms, real time=314.00ms, gc time=24.90ms
```

To recover the pseudo inverse with original data do

```Rewrite := [
A = (D__pile*W[1] . E__c)/3000,
B = (D__pile*W[2] . E__c)*89^(1/2),
C = (D__pile*W[3] . E__c)/1000,
F = (D__pile*W[4] . E__c)*89^(1/2)
]:

eval(PseudoInverse, Rewrite):```

InverseMatrix_mmcdara.mw

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