# Logical operator not evaluating correctly

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Andrew on 26 Jan 2023
Answered: Star Strider on 26 Jan 2023
Given the provided array X, create an array Y that is:
equal to 0 if the corresponding element of X is between -5 and +5, inclusive
equal to -1 if the corresponding element of X is less than -5
equalt to +1 if the corresponding element of X is greater than 5
Here is what I have:
Y = (~(X >= -5 & X <= 5) | (-1*(X < -5)) | (X>5)).
Why is the X < -5 not evaluationg to -1?

Star Strider on 26 Jan 2023
Only two comparisons are actually required here —
X = linspace(-7, 7, 15);
Y = -(X < -5) + (X > 5);
Check_Result = [X; Y]
Check_Result = 2×15
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 -1 -1 0 0 0 0 0 0 0 0 0 0 0 1 1
.

Walter Roberson on 26 Jan 2023
A|B is an or test and returns a logical value -1 is nonzero which is considered true, and since you or everything together you are going to end up with logical true for those entries.
Try adding the results of the computation

Les Beckham on 26 Jan 2023
I would do this in separate steps.
X = randi([-20, 20], [1 15])
X = 1×15
3 -6 2 6 -7 -8 -7 13 17 -3 5 -13 -17 5 -1
Y = zeros(size(X));
Y(X < -5) = -1;
Y(X > 5) = 1
Y = 1×15
0 -1 0 1 -1 -1 -1 1 1 0 0 -1 -1 0 0