The expression parser is hard to understand --- x(y) can be multiplication or a function depending whether y is numeric and various other context attributes. The "alternate form" does not evaluate to the original form! In order to explain the bug, I think you'd have to imagine the expressions being represented in memory in a way that preserves the ambiguity of n*(1/3) and n(1/3). The system tries to factor out n^3, gets n + (n(1/3)/n^3, and then tries to undo the operation by multiplying through by n^3. In doing this, it multiplies the function symbol n as though it were a variable. This causes the function symbol to be replaced by n^4. Inexplicably, it also cancels the n^3 in the denominator. On the bug vs. feature scale, this pegs out on the bug side. Hilarie
From: Emma Cohen <emma@don-eve.dyndns.org> Date: Mon, 17 Sep 2012 20:26:13 -0400 To: math-fun <math-fun@mailman.xmission.com> Subject: [math-fun] Huh? Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit
Can someone explain the results here? http://www.wolframalpha.com/input/?i=n%5E4+%2B+n%281%2F3%29 I can come up with a hypothesis which explains some of the results, but can't think of anything at all which would explain the "alternate form."
Any ideas? --Emma Cohen _______________________________________________