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Jan 08, 2019
03:26 AM

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Jan 08, 2019
03:26 AM

Setting up eigenvalue in mathcad

to all

I am struggling to set up the eigenvalue described in the attached mcad v15 sheet (or pdf). Could someone who understand these things enlighten me?

Thanks

Regards

7 REPLIES 7

Jan 08, 2019
04:34 AM

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Jan 08, 2019
04:34 AM

Is something like the attached what you are looking for?

Alan

Jan 08, 2019
08:00 AM

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Jan 08, 2019
08:00 AM

Thanks for the input. Appreciated. Looks like I do not quite fully understand the equation (yet) as if one plots the results of the eigenvalue extraction the result is not what I expected. I attached a typical example of such plot

Jan 08, 2019
10:16 AM

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Jan 08, 2019
10:16 AM

Hi,

The matrices A and B are singular, so it is not possible to calculate the eigenvalues.

Jan 08, 2019
01:43 PM

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Jan 08, 2019
01:43 PM

Thanks. Is it my test vector which is not correct? (does not work with 1 vector !) Do I need more vectors to make it work?

Jan 08, 2019
02:10 PM

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Jan 08, 2019
02:10 PM

You must make sure that | A | and of | B |, be different from zero. As you can see, in my calculations, I haven't multiplied by the matrix M when creating the matrices A and B. Mathcad defines an array as column vector and, consequently, the transpose is a row vector. It follows that HTMH is a scalar, and the eigenvalues equation looses meaning. You should reconsider the whole theory and how the text book defines the array (column or row?).

Jan 24, 2019
09:02 AM

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Jan 24, 2019
09:02 AM

Thanks for that. The theory part is pasted in the originally posted mcad sheet. I suspect that where [Hr(w)] is specified it's a matrix and I set-up my test with a vector ! One member corrected xv to XV from my original post to make it a matrix to make it work. I still don't know what sort of result to expect.

Jan 24, 2019
10:38 AM

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Jan 24, 2019
10:38 AM

Hi,

I would like to remind you that the algebra of matrices is a non-commutative algebra (A*B≠B*A) and in which only the operations of sum, subtraction, multiplication and inversion are defined (the division between matrices is not defined). You provide only the vector xv, there is no way to continue. In the text you provide, H is defined as a complex (No * Ni) matrix, and nothing else.