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Linear algebra - coordinates.

  • Thread starter frasifrasi
  • Start date
276
0
Can anyone explain exactly how you are supposed to apply coodinates in matrices? I am somewhat lost in class.

For example say, i have the coordinates A =
1 2
0 2 --> this is a 2 X 2 matrix


and I have to apply this to the basis

B =
1 0
0 0,

0 1
0 0,

0 1
0 1


-> The book gives the following matrix as the answer:

1 0 0
0 1 1
0 0 1

- But I still don't get how they got here. Can anyone outline the process?

Thank you!
 

Answers and Replies

HallsofIvy
Science Advisor
Homework Helper
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No, I have no idea what you are talking about. (And I thought I knew a little about Linear Algebra!) I have never heard of "applying coordinates" to matrices, nor do I see how you are going from 2 by 2 matrices to a 3 by 3 matrix. Could you state the problem exactly as it is given?
 
276
0
I am sorry, this is supposed to be a change of basis problem. We are changing B to basis A.

Can you help?
 
276
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we are trying to find the change of basis matrix.
 
HallsofIvy
Science Advisor
Homework Helper
41,736
894
From what basis to what basis? And what space? The matrices you list as a basis are NOT a basis for M4, because there are only 3 of them.
 
276
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from B to A. Please help me. The question asks for the change of basis matrix.

No other info is given.
 
276
0
Please help me brothers.
 
HallsofIvy
Science Advisor
Homework Helper
41,736
894
Honestly, the problem, as you stated it, still makes no sense to me. You have given us 3 matrices which you say is a basis (of what space? The space of all 2 by 2 matrices is 4 dimensional so it can't have a basis of 3 matrices) and ask for a "change of basis matrix". What is the basis to change to?
 

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