MATLAB: How to extract the upper triangular part of a matrix and set only the off-diagonal values to pi

matrixtriangulartriu

Hi all,

I got a matrix A = ones(1,1).

When I use triu(ones(1,1)) the lower triangular part of the matrix gets zero.

What I need to do is that instead of zero it gets pi.

That means: 1 1 1 pi 1 1 pi pi 1

Is there any possibility to integrate this into the triu function?

Thanks!

Best Answer

Your statements make no sense: ones(1,1) wil give you the scalar 1 ...

I think you are after something like this:

N = 3
A = ones(N)
tf = tril(true(N),-1)
A(tf) = 2

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Consider the variables x and y with standard deviations 2 and 3 and correlation coefficient 0.6. The corresponding matrices are (cut and paste into the command line)

STDxy = [ 2 0 ; 0 3 ] CORxy = [ 1 0.6 ; 0.6 1 ]

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Hope this helps.

Greg P.S. If one of the standard deviations is zero, replace inv with pinv.

Best Answer

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