Sort out square numbers

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Ambro Chunky
Ambro Chunky 2020-12-9
评论： Walter Roberson 2021-10-28
(Homework) Create an array of N numbers. Now find a single MATLAB statement that picks out from that array the 1,4,9,16,…,√Nth entries, i.e. those numbers which have indices that are square numbers.
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Kakande Hannington
Kakande Hannington 2021-10-28
We need serious help on this one as it's not easy
Walter Roberson
Walter Roberson 2021-10-28
Ran in:
@Kakande Hannington
Hint:
sqrt(65)
ans = 8.0623
take the 8 part if it
8
ans = 8
square that
8^2
ans = 64
does that equal the original number 65?
What about 121?
sqrt(121)
ans = 11
take the 11 part of it
11
ans = 11
square that
11^2
ans = 121
does that equal the original number 121?
By using this logic, if you had the index of a value in a vector, you could detect whether the index is the square of an integer. Comparisons ("does that equal") can return a logical vector, which you can then use to index the original array.
(Not saying this is the easiest way!)

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