For x = -i, square(x) = -1, sqrt(square(x)) = i. Meanwhile, abs(x) = 1. You're r... | Hacker News

Hacker Newsnew | past | comments | ask | show | jobs | submit

		yorwba 3 hours ago \| parent \| context \| favorite \| on: Why Mathematica does not simplify sinh(arccosh(x)) For x = -i, square(x) = -1, sqrt(square(x)) = i. Meanwhile, abs(x) = 1. You're right that it simplifies to abs(x) for real x, but that no longer holds for arbitrary complex values.

		help

NooneAtAll3 41 minutes ago [–]

for arbitrary complex values sqrt() gives 2 answers with +- signs

so sqrt(square(-i)) = +-i, one of which is x

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact