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Student Support Forum: 'Matrix output - can't reduce' topicStudent Support Forum > General > "Matrix output - can't reduce"

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Author Comment/Response
Peter
10/01/06 06:34am

Hi David,

1.) how did you manage to get no syntax errors, when using [M11,...] instead of {{M11,M12},{...}}?

2.) don't use "*" for matrix multiplication.
2.a) use "Dot" instead: A.M

FullForm[A*M] shows in version 5.2:
List[List[Times[A11,M11],Times[A12,M12]],List[Times[A21,M21],Times[A22,M22]]]
(which is {{A11*M11, A12*M12}, {A21*M21, A22*M22}})

and FullForm[A.M] displays as:
List[List[Plus[Times[A11,M11],Times[A12,M21]],
Plus[Times[A11,M12],Times[A12,M22]]],
List[Plus[Times[A21,M11],Times[A22,M21]],
Plus[Times[A21,M12],Times[A22,M22]]]]
which is more readable, without FullForm:
{{A11*M11 + A12*M21, A11*M12 + A12*M22},
{A21*M11 + A22*M21, A21*M12 + A22*M22}}

I'm sorry, I can't reproduce the described behaviour.

Peter


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Thread 'Matrix output - can't reduce' is now CLOSED
Author Date Posted
Matrix output - can't reduce David File 09/30/06 11:54am
Re: Matrix output - can't reduce Peter 10/01/06 06:34am
Re: Matrix output - can't reduce David File 10/02/06 1:08pm
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