CODEWITHSUNDEEP
matlabfor-loopeval
arabhi manachra
arabhi manachra

Reputation: 137

Summing elements within an eval statement, in a for loop

I have written a complete code that runs in MATLAB, but outputs a slightly incorrect result. I need to get the following:

utotal

where

utotal = S1plot + S2plot + ...

until the digit equals (N/2) + 1, where N is even. If N = 10, say, the digit would be 6.

Then I need to evaluate utotal within the script. How can I achieve this?

This is what I have so far: 

N = 10;
for alpha = 1:(N/2+1)
    eval(['utotal = sum(S' num2str(alpha) 'plot);'])
end

but it doesn't work because it evaluates the following:

utotal = sum(S1plot);
utotal = sum(S2plot);
utotal = sum(S3plot);
utotal = sum(S4plot);
utotal = sum(S5plot);
utotal = sum(S6plot);

Thanks in advance for help.

Upvotes: 0

Views: 67

Answers (3)

Autonomous
Autonomous

Reputation: 9075

See the comments by @beaker. This solution does not do what the OP wants.

I haven't tested this but it should work.

N=10;
for alpha = 1:(N/2+1)
    allSum = [allSum 'sum(S' num2str(alpha) 'plot)+'];
end

allSum(end)=';';
eval(['utotal = ' allSum]);

Upvotes: 1

beaker
beaker

Reputation: 16821

Here's a workaround you can use for now. Note that this is extremely bad coding practice and the difficulty you're having now is only one of the reasons you shouldn't do it.

%// Generate random data
S1plot = randi(100,51,5);
S2plot = randi(100,51,5);
S3plot = randi(100,51,5);
S4plot = randi(100,51,5);
S5plot = randi(100,51,5);
S6plot = randi(100,51,5);
N = 10;

%// Put individual matrices into 3D matrix S
%// To access matrix Snplot, use S(:,:,n)
%// This is the format these variables should have been in in the first place
for alpha = 1:(N/2+1)
    eval(['S(:,:,' num2str(alpha) ') = (S' num2str(alpha) 'plot);'])
end

%// Now sum along the third dimension
utotal = sum(S,3);

Upvotes: 2

Tarek
Tarek

Reputation: 697

N = 10;
Result =0;
for alpha = 1:(N/2+1)
   Result = Result + num2str(alpha)
end
eval(['utotal = sum(S' Result 'plot);'])

Upvotes: 0

Related Questions