Re: plot bug
- To: mathgroup at smc.vnet.net
- Subject: [mg16684] Re: plot bug
- From: "Stephen P Luttrell" <luttrell at signal.dra.hmg.gb>
- Date: Sat, 20 Mar 1999 02:08:58 -0500
- Organization: Defence Evaluation and Research Agency
- References: <7ct4md$873@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Arnold Knopfmacher wrote in message <7ct4md$873 at smc.vnet.net>...
>Using Mathematica 3.0 on a Mac and on a PC, the following command
>
>Plot[Cos[Degree Tan[Degree Sin[x]]],{x,0,2 Pi}]
>
>produced a graph whose y axis labels were ALL 1.
>Any explanation?
That's because the function Cos[Degree Tan[Degree Sin[x]]] evaluates to give
values that are veeery close to unity.
For instance, if you evaluate this function to 10 digits at one of its peaks
and one of this troughs you get the following results:
Peak:
Cos[Degree Tan[Degree Sin[\[Pi]]]]//N[#,10]& evaluates to give
1.
Trough:
Cos[Degree Tan[Degree Sin[\[Pi]/2]]]//N[#,10]& evaluates to give
0.9999999536
I guess that Plot rounds these both to 1.0
Stephen P Luttrell
Signal Processing and Imagery Department
DERA Malvern, St.Andrew's Road
Malvern, United Kingdom, WR14 3PS
+44 (0)1684 894046 (tel)
+44 (0)1684 894384 (fax)
luttrell at signal.dera.gov.uk (email)