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How to take logical or of all the elements in the vector without a loop?

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Jay Vaidya
Jay Vaidya on 16 Nov 2020
Commented: KSSV on 16 Nov 2020
I am trying to use
or(a(1,1):a(1,size(a,2)))
but it doesn't run for more than 2 elements.
also when I run
or(1,1,0,0.1,0,1)
it doesn't run. It only runs for 2 inputs i.e.
or(1,0)
Is there no direct way that I can take the logical OR of elements a(1,1) to a(1,size(a,2))?

Accepted Answer

Ameer Hamza
Ameer Hamza on 16 Nov 2020
Edited: Ameer Hamza on 16 Nov 2020
or() is an operator just defined for two inputs. In case of multiple inputs, you can use any() which is equivalent to or of all elements
>> y = any([1,1,0,0,1,0,1])
y =
logical
1
Similarly, all() is equivalent to and of all elements
>> y = all([1,1,0,0,1,0,1])
y =
logical
0

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More Answers (1)

KSSV
KSSV on 16 Nov 2020
Note that you have two types of indexings in MATLAB.
  1. Indexing
This is a number and should be posittive integers greater than 0. If number is negative or fracation, it will throw error.
A = rand(1,10) ;
A(1) % first element
A(end) % last element
A(1:5) % elements from 1 to 5
A(-) % error
A(0) % error
2. Logical indexing
Here indices are 0 and 1's. This would be class of logical.
A = rand(1,10) ;
idx = A>0.5 ; % get elements greater than 0.5. 0 where conditon fails and 1 where condition mets.
A(idx) % this will pick the elements at the above condition satisfies

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Jay Vaidya
Jay Vaidya on 16 Nov 2020
Hello, probably I did not make it clear enough.
I want the ans = a(1,1) | a(1,2) | a(1,3) | a(1,4) incase of a 4 element vector.
In other words, I need to OR the elements
like 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0.
where v is the boolean OR operator.
KSSV
KSSV on 16 Nov 2020
a = [1 0 1 1 0 1 0 0 0 1 1 0 0 1 1 1 1 1 0 0 1] ;
b = a(1)|a(2) ;
for i = 3:length(a)
b = b|a(i) ;
end

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