How to create vector which is linear combination of a matrix

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aliza mustafa
aliza mustafa 2022-8-30
评论： aliza mustafa 2022-8-30
Hi,
I have my matrix M as:
M = [1,2,3; 4,5,6; 7,8,9];
I am trying to create a vector that is a linear combination of the columns of M. I am doing it this way:
vec= [2*M(:,1); 3*M(:,2); 4*M(:,3)];
Its resulting in:
vec =
2
8
14
6
15
24
12
24
36
It doesn't seem right to me. Can you please help me in that? Any help will be really appreciated. Thanks in advance.
  2 个评论
Karim
Karim 2022-8-30
You will need to expand a bit on why it doesn't seem right ... what would you expect as output?
aliza mustafa
aliza mustafa 2022-8-30
I was making mistake in making the vector. I got it done this way:
vec= 2*M(:,1) + 3*M(:,2) + 4*M(:,3);
Thanks :)

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采纳的回答

Matt J
Matt J 2022-8-30
Ran in:
Perhaps you instead meant to have,
M = [1,2,3; 4,5,6; 7,8,9];
vec=M*[2;3;4]
vec = 3×1
20 47 74

更多回答（1 个）

Chunru
Chunru 2022-8-30
Ran in:
M = [1,2,3; 4,5,6; 7,8,9]
M = 3×3
1 2 3 4 5 6 7 8 9
vec= sum([2*M(:,1) 3*M(:,2) 4*M(:,3)], 2)
vec = 3×1
20 47 74
% Alternatively
vec =M*[2; 3; 4]
vec = 3×1
20 47 74

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