Multiply each element of matrix with corresponding element of another matrix by not using loop. Is there any other more efficient way?

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Mak Dukan 2021-11-16

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评论： Mak Dukan 2021-11-16

采纳的回答： KSSV

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Hi everyone!

I have a simple and yet useful question, whose answer could reduce my amount of code (make it more efficient).

I have two matrices and each is of dimensions 1x31. The first matrix called "Prod_year" represents total yearly electricity production and the second one called "fundamental_price_level" is a price curve with future projected electricity prices. I need to multiply each corresponding element of "Prod_year" (x,y) with the correspinding element of "fundamental_price_level" (x,y) or price_floor (this is just one value) when needed. The resulting matices "Mer_EXP_rev", "SP_EXP_rev" and "CfD_EXP_rev" are three different revenue streams, assuming different assumptions about the payment methods to the power plant. These matrices are also all of dimensions 1x31.

Instead of using for loops I would like to economise and use something simpler. Therefore, is there a way to make my code more efficient?

FYI: the first code I am posting works

Price_floor = 45;
%Merchant EXP revenues
Mer_EXP_rev = zeros(1,31);
for x=1
    for y=1:31
        Mer_EXP_rev (x,y) = Prod_Year (x,y) * fundamental_price_level (x,y);
    end
end
%SP EXP revenu"#Cfes
SP_EXP_rev =zeros(1,31);
for x=1
    for y=1:31
        if fundamental_price_level(x,y) < Price_floor
           SP_EXP_rev(x,y) = Price_floor * Prod_Year (x,y); 
           
       elseif fundamental_price_level(x,y) > Price_floor
           SP_EXP_rev(x,y) = fundamental_price_level(x,y) * Prod_Year (x,y); 
           
       else fundamental_price_level(x,y) = Price_floor;
           SP_EXP_rev(x,y) = Price_floor * Prod_Year (x,y);
           
        end
    end
end
%CfD EXP revenues
CfD_EXP_rev = zeros(1,31);
for x=1
    for y=1:31
      CfD_EXP_rev (x,y) =  Price_floor * Prod_Year (x,y);
    end
end

I tried doing the below code for the case of "Mer_EXP_rev" but it did not work because I get an error saying "Error using * Inner matrix dimensions must agree."

Mer_EXP_Rev2 = zeros(1,31);
Mer_EXP_Rev2(1,1:31) =  Prod_Year(1,1:31) * fundamental_price_level (1,1:31);

I would appreciate yout help to learn how to handle matrix multiplication in a better way.

Thanks a lot for your time!

Mak

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Answer 1

KSSV 2021-11-16

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Mer_EXP_rev = Prod_Year.*fundamental_price_level;

Read about element by element operations.

https://in.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html#:~:text=%2D%20are%20unnecessary.-,Array%20Operations,location%20in%20the%20second%20operand.

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KSSV 2021-11-16

That case you can use logical indexing and avoid loops.

Mak Dukan 2021-11-16

在 MATLAB Online 中打开

How would you apply it to this code?

SP_EXP_rev =zeros(1,31);
for x=1
    for y=1:31
        if fundamental_price_level(x,y) < Price_floor
           SP_EXP_rev(x,y) = Price_floor * Prod_Year (x,y); 
           
       elseif fundamental_price_level(x,y) > Price_floor
           SP_EXP_rev(x,y) = fundamental_price_level(x,y) * Prod_Year (x,y); 
           
       else fundamental_price_level(x,y) = Price_floor;
           SP_EXP_rev(x,y) = Price_floor * Prod_Year (x,y);
           
        end
    end
end