Skip to main content
Werner_E
Werner_EAnswer
25-Diamond I
Apr 1, 2023 2:32 AM UTC

Just the determinant?

So how about a small modification in Alvaro's RREF?

Werner_E_0-1680316267529.png

Sure could be done more efficient, but for a quick hack it seems to work OK. No error  check (matrix square, etc.) is done. I simply changed the program to return 0 if no suitable pivot element could be found.

It also works symbolically, at least as long as only numbers are used. It fails symbolically when variables are used because the if-conditions can't be evaluated symbolically without knowing their actual values.

 

View in thread

18 replies

ttokoro
ttokoro21-Topaz I
21-Topaz I
Mar 30, 2023 11:37 PM UTC

Your code is ok. But your data A is not able to make A^-1 because the 0 0 3 9 and 0 0 5 15 are same.

ttokoro_0-1680219369354.png

 

 


image.pngimage.pngimage.pngimage.pngimage.png

Translate
t.t.
    lvl10720-TurquoiseAuthor
    20-Turquoise
    Mar 31, 2023 2:04 AM UTC

    Many thanks for your response, Ttokoro. My Mathcad 15 with your code is the following :

    I.PNG

     

                                                        ___

     

    II.PNG

      

         But I still got stuck to keep going to write a code for symbolic evaluate a DETERMINANT of a matrix above. My question is "How to write a code for SYMBOLIC evaluate a DETERMINANT of a matrix and with a Gauss-Jordan method or any other idea."

        Best Regards.

             Loi.

    Translate
    lvl10720-TurquoiseAuthor
    20-Turquoise
    Mar 31, 2023 12:48 PM UTC

       And a similar code using Gauss-Jordan method, in the forum, is :

     

    III.png

     

     

      But I would like to have a symbolic evaluate result is : ==> 0

    Translate
    Werner_E
    Werner_E25-Diamond IAnswer
    25-Diamond I
    Apr 1, 2023 2:32 AM UTC

    Just the determinant?

    So how about a small modification in Alvaro's RREF?

    Werner_E_0-1680316267529.png

    Sure could be done more efficient, but for a quick hack it seems to work OK. No error  check (matrix square, etc.) is done. I simply changed the program to return 0 if no suitable pivot element could be found.

    It also works symbolically, at least as long as only numbers are used. It fails symbolically when variables are used because the if-conditions can't be evaluated symbolically without knowing their actual values.

     

    Translate
      lvl10720-TurquoiseAuthor
      20-Turquoise
      Apr 1, 2023 3:38 AM UTC

      2.png

       

         I really appreciate your time and help, Werner. 😊 🤔 🙄 especially your explanation. 

      And I guess now it's time keep going with Alvaro's RREF and modify his CODE for inverse of a square matrix. ( I guess I would still be helped more ... ).

       Thanks again,

          Best Regards.

              Loi. 

      Translate
      lvl10720-TurquoiseAuthor
      20-Turquoise
      Apr 1, 2023 11:37 AM UTC

      A small modification in Tom Gutman's det( ) ?

       

      3.png

       

      for symbolic evaluate result.

      Translate
      Terms & ConditionsAccessibility statement