# How index using inequalities

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Danny Maefengea on 21 Jun 2020
Commented: Danny Maefengea on 22 Jun 2020
Hello guys, I was doing this exercise and when I tried running my script, errors appeared.
Create a 1*100 vector A with random numbers from 0 to 10
A = randi([0,10],1,100)
Display all the numbers in A that are greater than 5
u = disp(A>5)
Delete all the numbers in A that are greater than 5
u = []

Walter Roberson on 22 Jun 2020
A>5 creates a logical vector, with each entry being true if the corresponding A was (strictly) greater than 5, and false if the corresponding A was less than or equal to 5.
disp(A>5) would display that logical vector.
To display the contents of A where A > 5 you need to use A>5 to select entries out of A using logical indexing.
However... disp() does not return any value, and it is an error to attempt to assign disp() to a variable.
u = []
If you had assigned u the parts of A that are greater than 5, then u = [] would just empty out that array, without changing A. You again want to use logical indexing

Danny Maefengea on 22 Jun 2020
thank you sir. So just need to put A inplace of "SomeArray" right?
Walter Roberson on 22 Jun 2020
Well you will need to define the logical_mask as well.
Danny Maefengea on 22 Jun 2020
oh okay thanks