MATLAB: Multiply nth elements of an array by an element of a different array

arrayelementif conditionMATLABmultiplication

I have the following code.
I would like it to work such that if the first element of Ox is greater than zero, which in this case it is, the 1st, 5th, 9th, 13th, 17th, 21st, 25th, etc up to the end of Array will be multiplied by the first element of Ox.
So the output would be:
AllOx1 = (0.5 1 1 1 0.5 1 1 1 0.5 1… etc)
Ox = [0.5 0 0 0];
Array = ones(1,256);
 
AllOx1 = [];
if Ox(1) > 0
    AllOx1 = (Array(1:4:end)*Ru(1), 1, []);
end
Any help would be much appreciated!
Thank you

Best Answer

I'll presume the answer to Cyclist's 2nd Q? is to be unchanged...and the other is just using different variables for the posting...either way, the answer is essentially the one given removing some unnecessary fluff...but adding one critical piece:
A=ones(1,10);  Ox=[0.5 0 0];   % preliminaries...
% engine
B=A;                % must copy original else will be short unless mod(size(A),4)==0
if Ox(1)>0
  B(1:4:end)=B(1:4:end)*Ox(1);
end
>> B  % results...
B =
    0.5000    1.0000    1.0000    1.0000    0.5000    1.0000    1.0000    1.0000    0.5000    1.0000
>>
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