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18. Moore-Penrose Pseudoinverse of a Matrix example ( Enter your problem )
  1. Example `[[4,0],[3,-5]]` `("Formula " A^(+)=V Sigma^(+) U^T)`
  2. Example `[[1,0,1,0],[0,1,0,1]]` `("Formula " A^(+)=V Sigma^(+) U^T)`
  3. Example `[[4,0],[3,-5]]` `("Formula " A^(+)=A^T * (A*A^T)^(-1))`
  4. Example `[[1,0,1,0],[0,1,0,1]]` `("Formula " A^(+)=A^T * (A*A^T)^(-1))`
  5. Example `[[1,-2,3],[5,8,-1],[2,1,1],[-1,4,-3]]` `("Formula " A^(+)=(A^T*A)^(-1) * A^T)`

5. Example `[[1,-2,3],[5,8,-1],[2,1,1],[-1,4,-3]]` `("Formula " A^(+)=(A^T*A)^(-1) * A^T)`





Find Moore-Penrose Pseudoinverse ...
`[[1,-2,3],[5,8,-1],[2,1,1],[-1,4,-3]]`


Solution:
Pseudoinverse of a matrix A is `A^(+) = (A^T*A)^(-1) * A^T`

1. Find `A'`

`A^T` = 
`1``-2``3`
`5``8``-1`
`2``1``1`
`-1``4``-3`
T
 = 
`1``5``2``-1`
`-2``8``1``4`
`3``-1``1``-3`


2. Find `A'*A`

`A'×A`=
`1``5``2``-1`
`-2``8``1``4`
`3``-1``1``-3`
×
`1``-2``3`
`5``8``-1`
`2``1``1`
`-1``4``-3`


=
`1×1+5×5+2×2-1×-1``1×-2+5×8+2×1-1×4``1×3+5×-1+2×1-1×-3`
`-2×1+8×5+1×2+4×-1``-2×-2+8×8+1×1+4×4``-2×3+8×-1+1×1+4×-3`
`3×1-1×5+1×2-3×-1``3×-2-1×8+1×1-3×4``3×3-1×-1+1×1-3×-3`


=
`1+25+4+1``-2+40+2-4``3-5+2+3`
`-2+40+2-4``4+64+1+16``-6-8+1-12`
`3-5+2+3``-6-8+1-12``9+1+1+9`


=
`31``36``3`
`36``85``-25`
`3``-25``20`


3. Find the inverse matrix `(A'*A)^(-1)`

`|A'*A|` = 
 `31`  `36`  `3` 
 `36`  `85`  `-25` 
 `3`  `-25`  `20` 


 =
 `31` × 
 `85`  `-25` 
 `-25`  `20` 
 `-36` × 
 `36`  `-25` 
 `3`  `20` 
 `+3` × 
 `36`  `85` 
 `3`  `-25` 


`=31 xx (85 × 20 - (-25) × (-25)) -36 xx (36 × 20 - (-25) × 3) +3 xx (36 × (-25) - 85 × 3)`

`=31 xx (1700 -625) -36 xx (720 +75) +3 xx (-900 -255)`

`=31 xx (1075) -36 xx (795) +3 xx (-1155)`

`= 33325 -28620 -3465`

`=1240`


`Adj(A'*A)` = 
Adj
`31``36``3`
`36``85``-25`
`3``-25``20`


 = 
 + 
 `85`  `-25` 
 `-25`  `20` 
 - 
 `36`  `-25` 
 `3`  `20` 
 + 
 `36`  `85` 
 `3`  `-25` 
 - 
 `36`  `3` 
 `-25`  `20` 
 + 
 `31`  `3` 
 `3`  `20` 
 - 
 `31`  `36` 
 `3`  `-25` 
 + 
 `36`  `3` 
 `85`  `-25` 
 - 
 `31`  `3` 
 `36`  `-25` 
 + 
 `31`  `36` 
 `36`  `85` 
T


 = 
`+(85 × 20 - (-25) × (-25))``-(36 × 20 - (-25) × 3)``+(36 × (-25) - 85 × 3)`
`-(36 × 20 - 3 × (-25))``+(31 × 20 - 3 × 3)``-(31 × (-25) - 36 × 3)`
`+(36 × (-25) - 3 × 85)``-(31 × (-25) - 3 × 36)``+(31 × 85 - 36 × 36)`
T


 = 
`+(1700 -625)``-(720 +75)``+(-900 -255)`
`-(720 +75)``+(620 -9)``-(-775 -108)`
`+(-900 -255)``-(-775 -108)``+(2635 -1296)`
T


 = 
`1075``-795``-1155`
`-795``611``883`
`-1155``883``1339`
T


 = 
`1075``-795``-1155`
`-795``611``883`
`-1155``883``1339`


`"Now, "A'*A^(-1)=1/|A'*A| × Adj(A'*A)`

 = `1/(1240)` ×
`1075``-795``-1155`
`-795``611``883`
`-1155``883``1339`


 = 
`0.8669``-0.6411``-0.9315`
`-0.6411``0.4927``0.7121`
`-0.9315``0.7121``1.0798`


4. Find the inverse matrix `(A'*A)^(-1) * A'`

`((A*A')^-1)×A'`=
`0.8669``-0.6411``-0.9315`
`-0.6411``0.4927``0.7121`
`-0.9315``0.7121``1.0798`
×
`1``5``2``-1`
`-2``8``1``4`
`3``-1``1``-3`


=
`0.8669×1-0.6411×-2-0.9315×3``0.8669×5-0.6411×8-0.9315×-1``0.8669×2-0.6411×1-0.9315×1``0.8669×-1-0.6411×4-0.9315×-3`
`-0.6411×1+0.4927×-2+0.7121×3``-0.6411×5+0.4927×8+0.7121×-1``-0.6411×2+0.4927×1+0.7121×1``-0.6411×-1+0.4927×4+0.7121×-3`
`-0.9315×1+0.7121×-2+1.0798×3``-0.9315×5+0.7121×8+1.0798×-1``-0.9315×2+0.7121×1+1.0798×1``-0.9315×-1+0.7121×4+1.0798×-3`


=
`0.8669+1.2823-2.7944``4.3347-5.129+0.9315``1.7339-0.6411-0.9315``-0.8669-2.5645+2.7944`
`-0.6411-0.9855+2.1363``-3.2056+3.9419-0.7121``-1.2823+0.4927+0.7121``0.6411+1.971-2.1363`
`-0.9315-1.4242+3.2395``-4.6573+5.6968-1.0798``-1.8629+0.7121+1.0798``0.9315+2.8484-3.2395`


=
`-0.6452``0.1371``0.1613``-0.6371`
`0.5097``0.0242``-0.0774``0.4758`
`0.8839``-0.0403``-0.071``0.5403`


`:.` Moore-Penrose pseudoinverse `A^(+)=`
`-0.6452``0.1371``0.1613``-0.6371`
`0.5097``0.0242``-0.0774``0.4758`
`0.8839``-0.0403``-0.071``0.5403`





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