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Hi All,

New-again matlab user after a decade away; having trouble with raising a negative number to the power 0.

I recognise that:

- (-2)^0 = 1 and
- -2^0 = -1.

In my code, I am trying to populate a 5x5, row by row filling the columns with elements of one 1x5 row vector to the power of another 1x5 vector.

I have written a very basic, and probably inefficient way of doing this with two for loops, but when it comes to raising a negative number to the power 0 and storing it, I get 1 as opposed to what I think is correct; -1.

I presume Im missing something very basic but would really appreciate any help; Thank you!

k = [0:4]

x = [-2.0 3.0 9.0 2.0 25.0]

A = ones(5,5);

for row = 1:length(k)

for col = 1:length(k)

A(row,col) = x(col)^k(row);

end

end

This is what I get: But I think the top left should be -1 since -2^0 = -1

1 1 1 1 1

-2 3 9 2 25

4 9 81 4 625

-8 27 729 8 15625

16 81 6561 16 390625

Ameer Hamza
on 18 Nov 2020

Edited: Ameer Hamza
on 18 Nov 2020

You can do it without for-loop

k = 0:4;

x = [-2.0 3.0 9.0 2.0 25.0];

A = x.^(k.')

Also, x(col)^k(row) is equivalent to (-2)^0, not -2^0.

For example, what you you expect the output of following code to be

x = -2;

y = x^2

should y be 4 or -4?

TADA
on 18 Nov 2020

Edited: TADA
on 18 Nov 2020

Any arithmetic operation performed on variables will treat the variables as if it was wrapped with parentheses.

Try this simple example:

x = -2;

y = x^0

y = 1

In my opinion, this is the correct result, which takes into account the proper order of operations, but if you really want that to keep the original sign, you can multiply your result by the sign of the original number:

y = sign(x) * x^0

y = -1

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