Advanced Search

Question: Matrix Multiplication with 2D input

Question:Matrix Multiplication with 2D input

tomleslie 13821 Maple 2018
matrix
October 17 2018
2

Whilst trying to debug another problem on this site, this one

https://www.mapleprimes.com/questions/225688-How-To-Compute-Inverse-Of-A-Matrix-For

I came across a Maple bug(?) which was so serious, I thought either

  1. I'm being more than usually dim
  2. it needs it's own entry here, so that others can check

Problem can be summarized as:

When using 2D input, can the '.' character be used for simple matrix multiplication???? Because it isn't working for me!

Entering the '.' character places a bold, midline dot between the two arguments, but executing the result gives "Error unable to parse". Converting to 1-D input, no issues - everything works as expected.I should also point out that

  1. I never normally use 2D-input for my own work
  2. the attached worksheet executes correctly in Maple 2017.3, X86 64 WINDOWS, Sep 13 2017, Build ID 1262472.

If this is reproducible then wtf!

> 

restart; with(LinearAlgebra); kernelopts(version)

`Maple 2018.1, X86 64 WINDOWS, Jun 8 2018, Build ID 1321769`

 (1)
> 

A := RandomMatrix(2, 2); B := RandomMatrix(2, 2)

Matrix(2, 2, {(1, 1) = 44, (1, 2) = -31, (2, 1) = 92, (2, 2) = 67})

  

Matrix(%id = 18446744074378134462)

 (2)
> 

A.B

Error, unable to parse

"A*B;"

  
> 

LinearAlgebra:-Multiply(A, B)

Matrix(%id = 18446744074378136502)

 (3)
> 

A:= RandomMatrix(2, 2);
B:= RandomMatrix(2, 2);
A.B

Matrix(2, 2, {(1, 1) = -32, (1, 2) = -4, (2, 1) = -74, (2, 2) = 27})

  

Matrix(2, 2, {(1, 1) = -93, (1, 2) = -72, (2, 1) = -76, (2, 2) = -2})

  

Matrix(%id = 18446744074378132406)

 (4)
> 

 

Download matMulProb.mw
Please Wait...