Matrix indexing a column on TI-89 - Hewlett Packard

This is a discussion on Matrix indexing a column on TI-89 - Hewlett Packard ; Hi: A TI-89 question, but I don't know where else to ask (well there are probably forums, but I'm old school USENET). How to access a column of a matrix? The dumb thing can of course access a row, as ...

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  1. Matrix indexing a column on TI-89

    Hi:

    A TI-89 question, but I don't know where else to ask (well there are
    probably forums, but I'm old school USENET).

    How to access a column of a matrix?

    The dumb thing can of course access a row, as in:

    [[1,2,3][4,5,6]][1] Enter

    [1,2,3]

    But how can I index one of the 3 columns in this matrix to get for ex,
    the first column vector:

    [[1][4]] ???

    I suppose I will have to write a function for this. Just hoping there
    is a built-in syntax for this.


    Thanks.


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    ____________________________________
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    crobcREMOVETHIS@BOGUSsbcglobal.net
    NOTE, delete texts: "REMOVETHIS" and
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  2. Re: Matrix indexing a column on TI-89

    On Jul 17, 5:48*pm, Chris Carlen
    wrote:
    > Hi:
    >
    > A TI-89 question, but I don't know where else to ask (well there are
    > probably forums, but I'm old school USENET).
    >
    > How to access a column of a matrix?
    >
    > The dumb thing can of course access a row, as in:
    >
    > [[1,2,3][4,5,6]][1] Enter
    >
    > [1,2,3]
    >
    > But how can I index one of the 3 columns in this matrix to get for ex,
    > the first column vector:
    >
    > [[1][4]] ???
    >


    Good question.
    I do't tink there is a built in function for that,
    but defining one is easy. Obviously, one can use the row access with
    two transpositions to get the desired result.

    Or I just tested "define col(m,n)=subMat(m,1,n,rowDim(m),n)", which
    gives [1;3] for col([1,2;3,4],1) and [2;4] for col([1,2;3,4],2).
    I also tested it with non-square matrices, just to be sure I did not
    get the function arguments wrong, but they worked too.

    username@localhost

  3. Re: Matrix indexing a column on TI-89

    username localhost wrote:
    > On Jul 17, 5:48 pm, Chris Carlen
    > wrote:
    >> Hi:
    >>
    >> A TI-89 question, but I don't know where else to ask (well there are
    >> probably forums, but I'm old school USENET).
    >>
    >> How to access a column of a matrix?
    >>
    >> The dumb thing can of course access a row, as in:
    >>
    >> [[1,2,3][4,5,6]][1] Enter
    >>
    >> [1,2,3]
    >>
    >> But how can I index one of the 3 columns in this matrix to get for ex,
    >> the first column vector:
    >>
    >> [[1][4]] ???
    >>

    >
    > Good question.
    > I do't tink there is a built in function for that,
    > but defining one is easy. Obviously, one can use the row access with
    > two transpositions to get the desired result.
    >
    > Or I just tested "define col(m,n)=subMat(m,1,n,rowDim(m),n)", which
    > gives [1;3] for col([1,2;3,4],1) and [2;4] for col([1,2;3,4],2).
    > I also tested it with non-square matrices, just to be sure I did not
    > get the function arguments wrong, but they worked too.



    Thanks for the reply! I'll give that a whirl.



    --
    Good day!

    ____________________________________
    CRC
    crobcREMOVETHIS@BOGUSsbcglobal.net
    NOTE, delete texts: "REMOVETHIS" and
    "BOGUS" from email address to reply.

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