how can i multiply two matrices?

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Naseeba PP
Naseeba PP 2017-2-23
回答： Alicia Palmerin-Jimenez 2022-3-5
I have a matrix 'a' with size 3x3 and 'b' with size 3x1.i want to multiply the inverse of 'a' with matrix 'b'.I tried the below code but got an error "Matrix dimensions must agree". please help to solve this
a=[1 0 -3; 2 -2 1; 0 -1 3];
inv_a=inv(a);
b=[0;2;121];
c=inv_a.*b;
  2 个评论
Beder
Beder 2017-2-23
This code does not produce any error on my system. Maybe you have a variable called "inv" which overlays the function "inv"?
Walter Roberson
Walter Roberson 2017-2-23
Beder,
I suspect you are using R2016b, which introduced automatic vector expansion as if bsxfun() had been used.

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采纳的回答

Walter Roberson
Walter Roberson 2017-2-23
c=inv_a * b;
not .*
inv_a is a 3 x 3 matrix, and you want algebraic matrix multiplication by the 3 x 1 matrix b in order to get the 3 x 1 solution.

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Alicia Palmerin-Jimenez
no

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