Matlab - Storing data from a nested loop

Question

I would like to store the data from a double loop in a matrix (not a cell). I tried the following code (the function used in the inner loop here is just an example).

valuesforOPratio = zeros(41,1);
valuesforM = zeros(41,61);
NPVtotal=1;
for M = 40:100
for OPratio = 30:70;
NPVtotal = NPVtotal+1
valuesforOPratio(OPratio)=NPVtotal;
end
valuesforM(M) = valuesforOPratio
end
I get the following error:

 In an assignment  A(:) = B, the number of elements in A and B must be the same.

Error in sensitivity_opratio (line 10)
valuesforM(M) = valuesforOPratio

Any help on how to store the data in a matrix ? I guess this is rather easy but I am not getting there

BillBokeey · Accepted Answer · 2016-05-19 08:35:04Z

2

There are a few problems with you code :

1/ You define valuesforOPratio as a 41x1 Vector. However, in the inner nested loop, the subscripts OPratio go from 30 to 70, meaning when you write valuesforOPratio(OPratio)=NPVtotal; the size of your valuesforOPratio vector will increase to 70.

To rectify that, you might want to either :

Make your OPratio subscript go from 1 to 41 (i.e. for OPratio=1:41 ...)
Set the right subscript in the call mentionned above (i.e. valuesforOPratio(OPratio-29)=NPVtotal;)

2/ When you write valuesforM(M)=valuesforOPratio, you are trying to put a vector (valuesforOPratio) in a scalar element (valuesforM(M)).

To rectify that, you just need to specify that you want a whole column of valuesforM to be filled with the values in valuesforOPratio, i.e. :

valuesforM(:,M-39)=valuesforOPratio;

edited May 19, 2016 at 8:35

answered May 19, 2016 at 8:25

BillBokeey

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1 Comment

KiW Over a year ago

Thanks for your answer it works perfectly fine. If i would change both loops to "parfor" loops would it still work the same way ?

rideyourstyle · Accepted Answer · 2016-05-19 08:13:51Z

0

Your valuesforM is a 41 by 61 matrix. If you want to write a row or colum you should wirte valuesforM(M:) = valuesforOPratio or valuesforM(:M) = valuesforOPratio

I havent MATLAB here on my computer to check my answer, but it should help you to find the solution.

answered May 19, 2016 at 8:13

rideyourstyle

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1 Comment

KiW Over a year ago

thanks, now i get "subscripted assignment dimension mismatch .... " -any idea on that ?

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