Bug in Solve (Mathematica 9)

Question

The issue seems to be fixed as of Version 10.1.

Just came across the strangest bug under both Mathematica 9.0.0 and 9.0.1. If one enters:

Solve[m == p Sin[x] && -Pi/2 < x < Pi/2, x]

... then Mathematica whirrs and whirrs (running on my Mac Pro with OS X 10.6.8), and doesn't seem to produce any answer (I gave up after a few minutes). But if one changes symbol p to something that 'sorts' earlier than an m, such as an 'a' or 'b', then it works correctly:

Solve[m == b Sin[x] && -Pi/2 < x < Pi/2, x]

Solve::nsmet: This system cannot be solved with the methods available to Solve.

Obviously, one can add assumptions on p or b to make it solve, but that is not the issue being raised.

Is this just a Mac issue, or are others experiencing the same on other platforms?

Ah, I've seen this one before... I remember an answer/comment from Daniel saying that this was a hashing problem and cannot be fully fixed, but they address specific and common cases as they encounter them. — rm -rf, Feb 08 '13 at 19:04
Here's the post I was thinking of: http://stackoverflow.com/q/5402214 — rm -rf, Feb 08 '13 at 19:06
Different issue. The hashing one only causes a slowdown in dealing with large, deep expressions. Will investigate. — Daniel Lichtblau, Feb 08 '13 at 19:54
FWIW: same behavior in Windows version (Mathematica 9.0.0.0 under Windows 7) — stevenvh, Feb 09 '13 at 10:58
It seems that changing the letter p to any letter after m will reproduce the problem... — user58955, Jun 03 '15 at 21:16

score 7 · Answer 1 · answered Feb 10 '13 at 18:21

7

This has been confirmed and reported as a bug (see comments).

answered Feb 10 '13 at 18:21

Szabolcs

234,956
30
623
1,263

Related cleanup guidelines proposal – Szabolcs Feb 10 '13 at 18:21

Bug in Solve (Mathematica 9)

1 Answers1

Linked