how to do product summation

Question

adarsh 2018-1-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/376013-how-to-do-product-summation

编辑： Jan 2018-2-22

采纳的回答： Star Strider

在 MATLAB Online 中打开

L1=1;L2=2; L3=3; D1=2;D2=3; D3=5;

Then how will i do

C=(L1*D1)+(L2*D2)+(L3*D3)

in MATLAB using programming (similarly i have to do 350 number of L and D). Kindly help me out.

i was trying like this one;

sum=0
for i=1:3
C=Li*Di 
end

but couldn't succeed. kindly help

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Stephen23 2018-1-7

编辑：Stephen23 2018-1-7

"similarly i have to do 350 number of L and D"

Then you should put your data into matrices, and so make your task trival. The name MATLAB comes from "MATrix LABoratory", and not from "lets put data into lots of separate numbered variables and make our code slow and complex".

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Star Strider 2018-1-7

I intended to imply that in my Answer.

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Answer 1

Star Strider 2018-1-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/376013-how-to-do-product-summation#answer_299037

在 MATLAB Online 中打开

I would create vectors out of the ‘L’ and ‘D’ values, then multiply them using vector/matrix multiplication:

L1=1; L2=2; L3=3; D1=2; D2=3; D3=5;
L = [L1 L2 L3];
D = [D1 D2 D3];
C = L * D';

Note the transpose operator (') for ‘D’. That is necessary to produce the result you want.

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Star Strider 2018-1-8

As always, my pleasure.

Jan 2018-2-22

编辑：Jan 2018-2-22

@adarsh: Of course it would have been much easier, if you did not create numbers variables from the beginning. It is much easier to work with vectors, matrices and arrays. Please consider Stephen's valuable comment and read the link carefully.

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