Re: question
- To: mathgroup at smc.vnet.net
- Subject: [mg21191] Re: question
- From: "David Bailey" <dave-bailey at freeuk.com>
- Date: Fri, 17 Dec 1999 01:24:00 -0500 (EST)
- References: <831sjn$fj2@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Alexandru Tintea <alext at pluto.qteam.ici.ro> wrote in message news:831sjn$fj2 at smc.vnet.net... > In Mathematica Version 2.2. I can't write_and_evaluate Cos[2]*Sin[3] because > I receive a simple result: Cos[2]*Sin[3] > If I write Cos[0.2]*Sin[3.3] I receive a numeric result: 0.05756; > If I write Evaluate[Cos[0.2]]*Evaluate[Sin[3.3]] I receive a numeric result: > 0.05756; > If I write Evaluate[Cos[2]]*Evaluate[Sin[3]] I receive a literal result: > Evaluate[Cos[2]]*Evaluate[Sin[3]] > I set the path in the "init.m" file and I receive the same answers. > What can I do? > Thank You! > Mathematica never converts an exact quantity, such as Sin[2], to an inexact numerical value unless you explicitly request it. This makes sense, you would not want the series expansion to Sin[x] (say) to look like: x - 0.16666666666666666*x^3 + 0.008333333333333333*x^5 - 0.0001984126984126984*x^7 When you want Mathematica to convert to numbers wherever possible use N. For example: N[Cos[2]] (or, equivalently, Cos[2]//N ) will give you what you want. The Evaluate function performs a quite different operation, although its name does look promising! David Bailey Salford Software