multiplying row vector by a scalar

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Kay
Kay 2023-2-23
回答： the cyclist 2023-2-23
trying to multiply the third row of a matrix by another row, B:
A = data(3, ;).*B
where B is a row vector
Need help finding a way to multiply the 3rd row of my matrix by a scalar value, for example 100.
Is there a way to do this all in one line?
Thanks!

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回答（4 个）

VBBV
VBBV 2023-2-23
A = data(3, :).*B
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John D'Errico
John D'Errico 2023-2-23
@Kay
They both told you how to do EXACTLY that. Did you try it?
Kay
Kay 2023-2-23
Hi. Im sorry. Im a beginner and from my point of view, they didn't answer my question. I probably didn't word it well enough, and thats my fault. I wasn't trying to be rude. This response feels really harsh.

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the cyclist
the cyclist 2023-2-23
You needed a colon in place of that semicolon
A = data(3,:).*B
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John D'Errico
John D'Errico 2023-2-23
@Kay
They both told you how to do EXACTLY that. Did you try it?
Kay
Kay 2023-2-23
Hi. Im sorry. Im a beginner and from my point of view, they didn't answer my question. I probably didn't word it well enough, and thats my fault. I wasn't trying to be rude. This response feels really harsh.

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John D'Errico
John D'Errico 2023-2-23
Ran in:
I think @Kay needs an example.
A = ones(4,3)
A = 4×3
1 1 1 1 1 1 1 1 1 1 1 1
B = 1:3;
A(3,:) = A(3,:).*B
A = 4×3
1 1 1 1 1 1 1 2 3 1 1 1
  1 个评论
Kay
Kay 2023-2-23
Hi. Thanks for this. I think I probably didn't word my question well enough, this isn't what I'm looking for. But thanks for your response!

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the cyclist
the cyclist 2023-2-23
Ran in:
% Your matrix
M = magic(4)
M = 4×4
16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1
% Your scalar
scalar = 100;
% Multiply the third row of your matrix by your scalar
M(3,:) = scalar .* M(3,:)
M = 4×4
16 2 3 13 5 11 10 8 900 700 600 1200 4 14 15 1

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