How to get the absolute value of the a vector inside an array?

Hi there, I am trying to extract the absolute value of the column vectors inside an array, but it keep giving me the message: Array indices must be positive integers or logical values., for the following code:

absvec = [];
for a = 1:270
    for b =1:10
        abs(H{a,b}) = absvec (a,b),
    end
end

can anyone help me?

[Adam Danz]

Either that's not the error message you're getting or you shared the wrong code with us.

The error message returned by your code is "Index in position 1 exceeds array bounds." (r2019a) Of course this is happeneng because absvec is empty and you're trying to index it.

do you mean

 absvec (a,b) = abs(H{a,b}) % ???

[Ana Bianco]

I may have confused which came first, thank you!

Answer 1

[Sebastian Körner]

relly not sure if this is what your question is about but maybe it helps.

since you provided no data to your problem i created some example data myself.

 H ={[5,-6],[5,-6];[7,-8],[7,-8];[5,-6],[5,-6];[7,-8],[7,-8]};
 v=1;
for i=1:4
    for k=1:2
        h(:,v)=abs(H{i,k});
        v=v+1;
    end
end

input: cell array with cevtors in each cell

output: a vector with the absolute values of each vector of the cell array

[Ana Bianco]

That is just perfect! Exactly what I wanted.

Thanks Sebastian!

[Stephen23]

Simpler and more efficient with a comma-separated list:

>> out = abs(cat(1,H{:}))
out =
  5  6
  7  8
  5  6
  7  8
  5  6
  7  8
  5  6
  7  8

Timing (1e5 iterations):

Elapsed time is 13.833 seconds.  % nested loops
Elapsed time is 2.239 seconds.   % comma-separated list