Author 
Comment/Response 
Bill Simpson

04/01/13 10:44am
In Response To 'Re: Re: Re: Re: Help with creating matrix from ...'  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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