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Student Support Forum: 'Help with creating matrix from another matrix' topicStudent Support Forum > General > "Help with creating matrix from another matrix"

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Author Comment/Response
Bill Simpson
04/01/13 10:44am

In Response To 'Re: Re: Re: Re: Help with creating matrix from ...'
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One possible source of errors is the order of x,y in a[[x,y]] or a[[y,x]]. This

In[1]:= m = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}};
m[[1, 2]]

Out[2]= 2

shows that 1,2 is first row, second column and not first column, second row. Thus it is m[[y,x]] or m[[row,column]] if you think of x being horizontal across the screen from left to right and y being vertical from the top of the screen to the bottom. This problem can also appear with Table[expr,{x,1,3},{y,1,3}] instead of Table[expr,{y,1,3},{x,1,3}].

I realize I can sometimes not be careful with this and make errors when calculating with data that expects x and y ordering.

Please see if this might be a source of the error and when you provide me with the examples I will also check this possible error and correct it.

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Subject (listing for 'Help with creating matrix from another matrix')
Author Date Posted
Help with creating matrix from another matrix Anton Siswo 03/24/13 01:15am
Re: Help with creating matrix from another matrix Bill Simpson 03/24/13 11:53pm
Re: Re: Help with creating matrix from another ... Anton Siswo 03/25/13 11:35am
Re: Re: Re: Help with creating matrix from anot... Bill Simpson 03/25/13 7:32pm
Re: Re: Re: Help with creating matrix from anot... Bill Simpson 03/25/13 10:20pm
Re: Re: Re: Re: Help with creating matrix from ... Anton Siswo 03/31/13 7:22pm
Re: Re: Re: Re: Re: Help with creating matrix f... Bill Simpson 04/01/13 00:06am
Re: Re: Re: Re: Re: Re: Help with creating matr... Anton Siswo 04/01/13 5:52pm
Re: Re: Re: Re: Re: Help with creating matrix f... Bill Simpson 04/01/13 10:44am
Re: Re: Re: Re: Re: Re: Help with creating matr... Anton Siswo 04/08/13 04:52am
Re: Re: Re: Re: Re: Re: Re: Help with creating ... Bill Simpson 04/09/13 8:35pm
Re: Re: Re: Re: Re: Re: Re: Re: Help with creat... Anton Siswo 04/11/13 10:58am
Re: Re: Re: Re: Re: Re: Re: Help with creating ... Bill Simpson 04/09/13 9:54pm
Re: Re: Re: Re: Re: Re: Re: Re: Help with creat... Anton Siswo 04/10/13 9:41pm
Re: Re: Re: Re: Re: Re: Re: Re: Re: Help with c... Bill Simpson 04/12/13 00:35am
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Help wi... Anton Siswo 04/16/13 07:19am
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Hel... Bill Simpson 04/16/13 7:48pm
Re: Help with creating matrix from another matrix Anton Siswo 03/26/13 11:29pm
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