create For Loop for a summation

Question

Giovanni Curiazio 2022-11-3

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1842503-create-for-loop-for-a-summation

评论： Giovanni Curiazio 2022-11-10

采纳的回答： Suman

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Hello, I need to write a code in matlab for the following summation:

Where m_i and DeltaQ_d are randomly created arrays. I created the following code but I think it is wrong

N=100

D=rand(N,1,'single'); % vettore detriti di 100 numeri casuali tra 0 e 1
somma=sum(D); 
m_i=(D/somma)*Mv; %massa casuale dei detriti
ver=sum(m_i); % verifica che la somma dei dei 100 pezzi razionalizzati restituisce il peso del velivolo
vx_i = randn(N,1,"single"); % componenti random di velocità nelle tre direzioni
vy_i = randn(N,1,"single"); 
vz_i= randn(N,1,"single");
DeltaV_id= [vx_i,vy_i,vz_i]; % matrice velocità i-esima detriti

DeltaQ_err=0;
for k=1:N
    T=sum(m_i.*DeltaV_id)
    DeltaQ_err= DeltaQ_err+T(k)
end
DeltaQ_err

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Suman 2022-11-8

Hi Giovanni,

Can you please provide the value of "Mv"?

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Answer 1

Suman 2022-11-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1842503-create-for-loop-for-a-summation#answer_1094763

在 MATLAB Online 中打开

Hi Giovanni,

I am assuming the value of "Mv" to be a scalar and the summation equation to be the following:

As per the above summation equation, the "For" loop logic that you have written doesn't match with the equation logic.

You can use the following code snippet instead of the existing "For" loop:

DeltaQ_err = 0;
for k = 1:N
    T = m_i(k) * DeltaV_id(k);
    DeltaQ_err = DeltaQ_err + T;
end
DeltaQ_err

I hope this information is helpful to you.

Cheers,

Suman

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Giovanni Curiazio 2022-11-10

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Thanks a lot. Yes Mv in scalar. This is how i did, it's almost the same as yours:

DeltaQ_err=zeros(1,3);
DeltaQ=zeros(N,3); %inizializzo matrice 
for k=1:N
    DeltaQ(k,:)=(m_i(k)*DeltaV_id(k,:));  
    DeltaQ_err=DeltaQ_err+DeltaQ(k,:);
end
DeltaQ_err