RATPOW Raise to rational power.

RATPOW(X,A,B) raises each element of array X to the power of its
corresponding element in array A./B, where both A and B must be
integers. Elements of B corresponding to negative elements of X must
be odd.

RATPOW(X,R) for real R, is same as RATPOW(X,A,B) where [A,B] = RAT(R).

Input arguments must be floating point arrays of reals.

See also radical,realpow.

Example:

>> x = [-1 -64; 81 32]; a = [1 1;2 2]; b = [3 3;4 5];
>> ratpow(x,a./b)

ans =

-1 -4
9 4

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>> x.^(a./b)

ans =

0.5000 + 0.8660i 2.0000 + 3.4641i
9.0000 4.0000

>> realpow(x,a./b)
??? Error using ==> realpow
Realpow produces complex result.
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