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[MUG] convert question

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[MUG] convert question
Author: Carl Eberhart    Posted: Sun, 13 Oct 2002 11:34:29 -0400
>> From: Carl Eberhart "carl" Converting between matrices, lists, vectors and Matrices, Vectors works well. But converting from a list to a matrix (in Maple 8 and Maple 7) returns an error convert([2,1,3],matrix); Error, (in convert/matrix) expecting array, rtable or list It would be convenient if Maple would return matrix([[1,2,3]]) Carl Eberhart, Mathematics 859-257-1258 University of Kentucky 759 POT Lexington, Ky 40506 http://www.msc.uky.edu/carl

[MUG] Re: convert question
Author: Maple User Group    Posted: Fri, 18 Oct 2002 17:35:12 -0400
>> From: Maple User Group "maple_gr" | >> From: Carl Eberhart "carl" | Converting between matrices, lists, vectors and Matrices, Vectors | works well. But converting from a list to a matrix (in Maple 8 and | Maple 7) returns an error | | convert([2,1,3],matrix); | Error, (in convert/matrix) expecting array, rtable or list | | It would be convenient if Maple would return matrix([[1,2,3]]) -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=- Date: Tue, 15 Oct 2002 15:37:41 -0700 (PDT) From: Robert Israel "israel" To: "maple-list" Subject: convert question But maybe it should be matrix([[1],[2],[3]]). How is Maple to know if you want your list interpreted as a row or as a column? BTW, convert([2,1,3],Matrix) does work (and results in a row). Robert Israel "israel" Department of Mathematics http://www.math.ubc.ca/~israel University of British Columbia Vancouver, BC, Canada V6T 1Z2 -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=- Date: Tue, 15 Oct 2002 22:01:12 -0400 From: "Douglas B. Meade" "meade" To: "maple-list" Subject: convert question Carl and MUG, The problem, of course, is that Maple does not know the dimension of the matrix that you want it to create. One possible workaround is to convert to a vector, then convert the vector to a matrix. This returns a COLUMN matrix, not a row matrix. If you really want a row matrix, use transpose: > L := [1,2,3]; L := [1, 2, 3] > Lv := convert(L,vector); Lv := [1, 2, 3] > Lm := convert( L, matrix ); Error, (in convert/matrix) expecting array, rtable or list > Lvm := convert( Lv, matrix ); [1] [ ] Lvm := [2] [ ] [3] > Lm_row := linalg[transpose]( convert( convert( L, vector ), matrix ) > ); Lm_row := [1 2 3] This last result could be taught to convert so that convert( L, matrix ) would do this. Or, you could write your own convert procedure: > convertLtoM := (L::list) -> > linalg[transpose](convert(convert(L,vector),matrix)): > convertLtoM( L ); [1 2 3] I hope this is of some use to you, Doug ----------------------------------------------------------------------- Douglas B. Meade Phone: (803) 777-6183 FAX: (803) 777-6527 Department of Mathematics URL: http://www.math.sc.edu/~meade/ USC, Columbia, SC 29208 E-mail: "mailto:meade" -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=- From: "Peter Weigand" "peter.weigand" To: "maple-list" Date: Wed, 16 Oct 2002 10:27:54 +0200 Subject: convert question The conversion is possible in two steps convert([2,1,3], array):convert(%,matrix): The result is a 3x1 column. With regards Peter Weigand----------------------------------------------------- Dr. Peter Weigand, Chemnitz University of Technology Faculty of Mathematics Mail :D-09107 Chemnitz, Germany Phone: +49 0371 531 2655 Fax : +49 0371 531 4947 E-mail: "weigand" _____________________________________________________ -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=- Date: Thu, 17 Oct 2002 09:37:21 +0100 Subject: convert question To: "maple-list" From: John Trapp "j.j.trapp" Try >convert( [ >[2,1,3] ] >,matrix); or >convert( [ >[2 ] >, [ >1 ] >, [ >3 ] >],matrix); Maple does not know whether you require a 1x3 or 3x1 matrix. John Trapp -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=- Date: Thu, 17 Oct 2002 10:00:45 -0400 (EDT) From: Carl Devore "devore" To: "maple-list" Subject: convert question But what if it would be convenient for someone else if it returned matrix([[1],[2],[3]])? If L is a list, what is so bad about saying matrix([L]) or convert([L], matrix) to get what you want? Also Maple 8 allows convert(L, compose, Matrix, matrix) and `<|>`(L[]) returns a 1 x n Matrix (not matrix).

[MUG] Re: convert question
Author: Carl Eberhart    Posted: Mon, 21 Oct 2002 21:35:29 -0400
>> From: Carl Eberhart "carl" Thanks for all the suggestions. I wasn't being clear with my complaint. The command convert([1,2,3],matrix) returns the error expecting array, rtable or list But [1,2,3] is a list. I would be happy for maple to assume that I wanted a row matrix, otherwise I would have asked it to convert([[1],[2],[3]],matrix) But at least don't return that particular error message. Carl Carl Eberhart, Mathematics 859-257-1258 University of Kentucky 759 POT Lexington, Ky 40506 http://www.msc.uky.edu/carl

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