How magic square, magic() FUNCTION works for Negative Integers & 2(where it should not work) ?

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M.K.H. CHANDAN 2013-3-15

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https://ww2.mathworks.cn/matlabcentral/answers/67316-how-magic-square-magic-function-works-for-negative-integers-2-where-it-should-not-work

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In Matlab(7.5): For -ve Odd order it is dispalying NULL matrix and for -ve Even order it is showing error.

??? Subscript indices must either be real positive integers or logicals.

For all other N > 0 & N !=2

 Magic square.
    MAGIC(N) is an N-by-N matrix constructed from the integers
    1 through N^2 with equal row, column, and diagonal sums.
    Produces valid magic squares for all N > 0 except N = 2.
    works perfectly

Can't we restrict the process of calling function from the satrt itself ?

as ??? Subscript indices must either be real positive integers or logicals and should not equal to 2.

For Example >> >> magic(-2) ??? Subscript indices must either be real positive integers or logicals.

Error in ==> magic at 41 M([i; i+p],j) = M([i+p; i],j);

>> magic(-3)

ans =

[]

MK harichandan >> Here Null Matrix instead of error.

>> magic(-4) ??? Error using ==> reshape Size vector elements should be nonnegative.

Error in ==> magic at 26 M = reshape(1:n*n,n,n)';

MK harichandan >> Here error after processing some methods.

>> magic(-1)

ans =

[]

>> magic(-12) ??? Error using ==> reshape Size vector elements should be nonnegative.

Error in ==> magic at 26 M = reshape(1:n*n,n,n)';

MK harichandan>> Here error after processing some methods.

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the cyclist 2013-3-15

I agree that the error-trapping of the magic() function leaves something to be desired. The fact that it returns a result for n=2, without warning or error, is particularly annoying.

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