MATLAB: A question about the for loop index

for loopMATLAB

Hello,

I would like to have a for loop with its index k ranging from e.g. 8 to 1 such that in the first iteration k=8, in the second iteration k=4, in the 3rd iteration k=2, and in the forth iteration k=1. I would appreciate your help. Thanks.

Best Answer

   for k=2.^(3:-1:0)
     ....
   end

Related Solutions

MATLAB: Question about vectorization using indexes

Note that ind and b must be transposed for this to work:

>> a   = [4;2;1;3;1;4;4;0]; % must be column!
>> ind = [1,0;2,3;4,0;3,3;5,3].'; % transposed!

>> b   = [5,0;2,2;1,0;2,2;2,2].'; % transposed!
>> idx  = b~=0;
>> XC = ind(idx);
>> bC =   b(idx);
>> [~,idc] = find(idx);
>> out = accumarray(idc,a(XC).^bC,[],@prod)
out =
  1024
  4
  3
  1
  1

MATLAB: Beginner question about for loops and indexing

Hi Callum,

You're really close.

First, you can move the "r = ... " line outside the loop to do the operation on the whole array at once.

Then inside the loop, you need to index the other variables the same way you did with "a(counter)".

So it looks like this:

a = 1:5:150; % array before function applied
b = zeros(1,30); % used to store numbers from a after functions
counter = 0;
r = rem(a,2); % r = 0 if number is even, r = 1 if number is odd
for series = [1:30]
    counter = counter + 1;
    if r(counter) == 0
       b(counter) = a(counter)*4; % if number in b is even, multiply it by 4
    elseif r(counter) == 1
           b(counter) = a(counter)^3; % if number in a is odd, cube it
    end
end

Best Answer

Related Solutions

MATLAB: Question about vectorization using indexes

MATLAB: Beginner question about for loops and indexing

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