Problem using Quotient and Mod functions with rational parameters
- To: mathgroup at smc.vnet.net
- Subject: [mg41860] Problem using Quotient and Mod functions with rational parameters
- From: eduault <eduault at yahoo.com>
- Date: Sat, 7 Jun 2003 00:08:49 -0400 (EDT)
- Organization: Guest of ProXad - France
- Sender: owner-wri-mathgroup at wolfram.com
As a Mathematica user, I was recently surprised by the result returned by the Quotient and Mod functions, called with some rational parameters. I was expecting that Quotient[m*n, n], with m positive integer and a positive would return m. This is nearly almost the case, for example: Quotient[0.12, 0.01] returns 12 Quotient[0.13, 0.01] returns 13 Quotient[0.14, 0.01] returns 14 However, for some parameters, this is not the case: Quotient[0.29, 0.01] returns 28 Quotient[0.57, 0.01] returns 56 Quotient[0.58, 0.01] returns 57 Quotient[0.59, 0.01] returns 58 Does someone explain those results, which I observed using Mathematica versions 4.0.1.0 and 4.0.2.0, and two different machines (PCs with Windows NT and Windows 98) ?? --------------------------------------------------------------------- Note: The same behavior occurs with the Mod function. This relation between Quotient and Mod is normal, because of the relation found in the documentation, saying that "Mod[m, n] is equivalent to m - n Quotient[m, n]". But this leads to some surprising results: Mod[m*n, n] should return 0, as in most cases: (I agree with this result) Mod[0.12, 0.01] returns 0 Mod[0.13, 0.01] returns 0 Mod[0.14, 0.01] returns 0 but we also have, for rare parameters: Mod[0.29, 0.01] returns 0.01 Mod[0.57, 0.01] returns 0.01 Mod[0.58, 0.01] returns 0.01 Mod[0.59, 0.01] returns 0.01