Info

此问题已关闭。 请重新打开它进行编辑或回答。

how to multiply matrix 2 * 2 if the elements of the matrix are row vectors.

1 次查看（过去 30 天）
Ed
Ed 2013-7-15
关闭： MATLAB Answer Bot 2021-8-20
Example:
fre=100:100:1000;
A1=1; B1=5; C1=0; D1=1;
Matrix1=[A1 B1;C1 D1];
A2=1; B2=sin(2*pi*fre); C2=0; D2=1;
Matrix2=[A2 B2;C2 D2];
MatrixTotal=Matrix1*Matrix2 ???
  4 个评论
显示 2更早的评论
Ed
Ed 2013-7-15
thanks... Shaun but please... tell me how..?? use a for loop to go through each element of fre ?
dpb
dpb 2013-7-16
Well, you've got to define precisely what it is you mean to multiply by what...you've got a square matrix of 2x2 and another that isn't regular and could only be written in Matlab as a cell array as containing a constant and a vector on one row and two constants on the second.
Now, what is the result wanted?
Give an actual demonstration using, say, only 3 values for the vector length. Perhaps even just working that out algebraically will give you the clue you need to write the Matlab code but even if not at least it will give the readers here an idea of what you mean...the crystal ball is cloudy this morning, sorry.

此问题已关闭。

回答（3 个）

Miroslav Balda
Miroslav Balda 2013-7-16
Your task is rather simple, and as a matter of fact , you have almost solve it. The a bit modified code is as follows:
% Ed.m 2013-07-16
A1=1; B1=5; C1=0; D1=1;
Matrix1=[A1 B1;C1 D1]
for fre=100:100:1000;
A2=1; B2=sin(2*pi*fre); C2=0; D2=1;
Matrix2=[A2 B2;C2 D2];
MatrixTotal=Matrix1*Matrix2
end
When you run the code you get:
>> Ed
Matrix1 =
1 5
0 1
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
MatrixTotal =
1.0000 5.0000
0 1.0000
The result is not surprising, because you get 10 times almost the same result as Matrix1. The reason is clear - sin(2*pi*integer)=0, what means that Matrix2 equals unity matrix. Why MatrixTotal does not equal Matrix1 exactly? The function sin(2*pi*fre) does not equal 0 precisely due to rounding errors in calculating sin of large argument.
It is all.
Mira
David (degtusmc)
David (degtusmc) 2013-7-16
Try converting to matrix and then multiplying using vec2mat. The link for the documentation is below, I hope this helps.
http://www.mathworks.com/help/comm/ref/vec2mat.html
Ed
Ed 2013-7-16
thanks .. I will review the information
  1 个评论
David (degtusmc)
David (degtusmc) 2013-7-31
Ed,
Make sure to let us know if your question was answered (by accepting one of the answers). This way, everyone else in the community can see that the question is "closed".
Thanks.

此问题已关闭。

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by