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AATaylor1-Visitor
1-Visitor
March 9, 2018
Solved

Determining Maximum Values per Row in a Matrix

  • March 9, 2018
  • 1 reply
  • 7396 views

Hi, 

 

I would like to write a program that determines the maximum values per row in a i by j matrix.

 

I have written the program below, but I am struggling to get it to work automatically, without having to manually add in the number of columns in the max() function on line 3 - please see attached. I thought the second example in the attachment maxrows2(VEC) was the same as maxrows(VEC); however it seems not....maxrows.PNG

 

I had an idea to try and split the matrix into column vectors and do it that way, as per the link below 

 

https://community.ptc.com/t5/PTC-Mathcad-Questions/Need-to-select-the-maximum-of-two-column-matrices-and-return-as/m-p/334430#M130735

 

However I am also having trouble writing a program to automatically split an i by j matrix into j columns!

 

Any help would be greatly appreciated.

 

Kind regards

Best answer by Werner_E

I just stumbled over your question and while I am not sur if you still need the help, here it is.

Your maxrows2 will always return the last column of the input matrix.

Here is a solution which automatically will deal with any number of rows. As Mathcad 15 does not provide a row selector, we have to transpose the matrix and use the column selector.

b.png

1 reply

W
Werner_E25-Diamond IAnswer
25-Diamond I
June 29, 2018

I just stumbled over your question and while I am not sur if you still need the help, here it is.

Your maxrows2 will always return the last column of the input matrix.

Here is a solution which automatically will deal with any number of rows. As Mathcad 15 does not provide a row selector, we have to transpose the matrix and use the column selector.

b.png

    A
    AATaylor1-VisitorAuthor
    1-Visitor
    June 29, 2018

    Yes, thank you - I hadn't found a solution for this, so I just did it the long way. This is really useful thank you.

    Although, if you wouldn't mind explaining, what does the <c> operator do in M^<c>?

    Many thanks and kind regards

    W
    Werner_E25-Diamond I
    25-Diamond I
    June 30, 2018

    the <c> operator is the column selector which I mentioned. You get it by typing Ctrl 6 or via the matric palette.

    It returns the column number c, a column vector. So this column vector is fed into the max functions which returns the max number of that vector.

    Mathcad 15 an below don't offer a row selector (Prime does - one of the few improvements in Prime) and thats the reason I had to transpose the matrix first.

    B.png

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