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pinv operation in matlab

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ANUSAYA SWAIN
ANUSAYA SWAIN on 20 Apr 2024
Edited: Bruno Luong on 20 Apr 2024
I have a matrix X of size [32X32X10]. I want to do pinv(X). But it suggested to use pagesvd(X). Now the dimension becomes [32X1X10]. However I want the matrix dimension to remain same that is [32X32X10].

Accepted Answer

Voss
Voss on 20 Apr 2024
X = rand(32,32,10);
XI = pageinv(X);
size(XI)
ans = 1x3
32 32 10
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  3 Comments
Steven Lord
Steven Lord on 20 Apr 2024
From the pagepinv documentation page: "Introduced in R2024a"
Bruno Luong
Bruno Luong on 20 Apr 2024
Thanks somehow I missed pagepinv when I looked up earlier.

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More Answers (1)

Bruno Luong
Bruno Luong on 20 Apr 2024
Edited: Bruno Luong on 20 Apr 2024
NOTE: This code is useful fonly or users who run version greater than R2021a and before R2024a, where pagesvd is supported by pagepinv is not..
A = pagemtimes(rand(4,2,5), rand(2,3,5)); % This should be your 32 x 32 x 10 matrix
piA = pagepinv(A)
piA =
piA(:,:,1) = -0.7143 -0.1994 0.8830 0.5803 3.6830 0.8982 -3.7827 -2.1157 -3.5004 -0.9739 4.3082 2.8220 piA(:,:,2) = 1.7339 -1.6101 0.2768 0.1140 -0.5683 0.8934 0.0456 0.2565 -1.1307 1.3152 -0.0816 0.1389 piA(:,:,3) = -0.7173 0.8751 0.5408 -0.0777 3.3456 -2.3089 -1.7138 0.8681 -1.6643 1.5736 1.0465 -0.3106 piA(:,:,4) = 11.6667 8.3580 -12.7967 -5.3279 -3.8216 -2.6054 4.4286 1.9206 -10.5258 -7.3566 11.8744 5.0506 piA(:,:,5) = -0.1933 0.0253 -0.3618 0.9475 -0.6336 -0.0070 -0.9652 2.2255 1.4941 0.2434 1.7190 -3.0276
% Check correctness
for k = 1:size(A,3)
norm(pinv(A(:,:,k))-piA(:,:,k),'fro')
end
ans = 0
ans = 0
ans = 0
ans = 0
ans = 0
function piA = pagepinv(A, tol)
sizeA = size(A);
m = sizeA(1);
n = sizeA(2);
if min(m,n) == 0
piA = zeros([n,m,sizeA(3:end)], 'like', A));
return
end
A = reshape(A,m,n,[]);
p = size(A,3);
[U,s,V]=pagesvd(A,'econ','vector');
if nargin >= 2
% user providestol, scalae or vector of length p
tol = reshape(tol, 1, 1, []);
else
smax = s(1,:,:); % ,porms of matrices
tol = max(m,n)*eps(smax);
end
s(s <= tol) = Inf;
S = reshape(s,1,size(V,2),p);
piA = pagemtimes(V./S,'none',U,'ctranspose');
piA = reshape(piA,[n,m,sizeA(3:end)]);
end
  2 Comments
Paul
Paul on 20 Apr 2024
Is this better than looping over the pages and calling pinv on each?
Bruno Luong
Bruno Luong on 20 Apr 2024
Edited: Bruno Luong on 20 Apr 2024
It's vectorized and potentially multithreaded via pagesvd, better I don't know. But it could be a stock function.

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