Re: Trig identity oscillations
- To: mathgroup at smc.vnet.net
- Subject: [mg47710] Re: Trig identity oscillations
- From: adam.smith at hillsdale.edu (Adam Smith)
- Date: Fri, 23 Apr 2004 02:30:38 -0400 (EDT)
- References: <c67q7l$gum$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
You are correct that Cos[t+5 Pi/6]/Sin[t+Pi/3] = 1.
What is happening is that the Plot function is numerical. As is
substitutes in various values for t you end up with a very small
number divide by another very small number. The rounding that occurs
in the numerical evaluations is what causes the unexpected behavoir.
Try Simplify[Cos[t+5 Pi/6]/Sin[t+Pi/3]] and you will find that
Mathematica returns the expected 1. In general it is useful to
simplify any complicated function before plotting.
Plot[Simplify[Cos[t+5 Pi/6]/Sin[t+Pi/3]],{t,0,2 Pi}]
Adam Smith
mathma18 at hotmail.com (Narasimham G.L.) wrote in message news:<c67q7l$gum$1 at smc.vnet.net>...
> Should it not be a more placid -1 ?
> Plot[Cos[t+5 Pi/6]/Sin[t+Pi/3],{t,0,2 Pi}]