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QUTADAh1-Visitor
1-Visitor
June 3, 2019
Solved

whats the difference

  • June 3, 2019
  • 6 replies
  • 3500 views

Hi guys as you see I am using this matrix and want to find eigenvalues and vector but dont understand the difference between two numeric and symbolic solutions, why are they different?

 

Thanks

Best answer by LucMeekes

You should realize that Mathcad contains a numeric processor an a symbolic processor. They approach your mathematical problem form a different standpoint, and therefore can produce different answers to the same problem.

 

Success!
Luc

6 replies

W
Werner_E25-Diamond I
25-Diamond I
June 3, 2019

On contrary to Eigenvalues, Eigenvectors are not unique. Every multiple of an Eigenvector is an Eigenvector, too.

So you are free to use (1;1) as eigenvector or (0.75; 0.75).

Mathcads numerics uses eigenvectors with length 1 while the symbolics doesn't normalizes that way.

 

For future questions: Instead or additionally to pics please always attach your worksheet.

 

    Q
    QUTADAh1-VisitorAuthor
    1-Visitor
    June 3, 2019

    Worksheet is usually long thats why i attach a pic instead..

    L
    LucMeekes23-Emerald IVAnswer
    23-Emerald IV
    June 3, 2019

    You should realize that Mathcad contains a numeric processor an a symbolic processor. They approach your mathematical problem form a different standpoint, and therefore can produce different answers to the same problem.

     

    Success!
    Luc

    Q
    QUTADAh1-VisitorAuthor
    1-Visitor
    June 3, 2019

    and how do I know which answer I want? thanks!

    W
    Werner_E25-Diamond I
    25-Diamond I
    June 3, 2019
    @QUTADAh wrote:

    and how do I know which answer I want? thanks!

    How should we know which answer you need?

    If you don't know why you calculate eigenvectors of a matrix and what you should do with them, you probably don't need to calculate them at all 😉

     

    The worksheet with the eigenvectors sure is not too large and if a worksheet you experience a problem with is too large or contains confident data, you should try to narrow down the problem and create a smaller example sheet which shows the problem/error, too. After all, its hard to debug just a picture and we often need a live worksheet to play with, to find the reason for an error or a suitable workaround.

     

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