Method on @infsup: power (X, Y)
Operator on @infsup: X .^ Y

Compute the general power function on intervals, which is defined for (1) any positive base X; (2) X = 0 when Y is positive; (3) negative base X together with integral exponent Y.

This definition complies with the common complex valued power function, restricted to the domain where results are real, plus limit values where X is zero. The complex power function is defined by exp (Y * log (X)) with initial branch of complex logarithm and complex exponential function.

Warning: This function is not defined by IEEE Std 1788-2015. However, it has been published as “pow2” in O. Heimlich, M. Nehmeier, J. Wolff von Gudenberg. 2013. “Variants of the general interval power function.” Soft Computing. Volume 17, Issue 8, pp 1357–1366. Springer Berlin Heidelberg. DOI 10.1007/s00500-013-1008-8.

Accuracy: The result is a tight enclosure.

infsup (-5, 6) .^ infsup (2, 3)
  ⇒ ans = [-125, +216]

See also: @infsup/pow, @infsup/pown, @infsup/pow2, @infsup/pow10, @infsup/exp.

Package: interval