Re: Mathmatica Problem...

• To: mathgroup at smc.vnet.net
• Subject: [mg14344] Re: Mathmatica Problem...
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Thu, 15 Oct 1998 00:28:47 -0400
• References: <6vuqt7\$8ju@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Mr D.J. Winstanley wrote in message <6vuqt7\$8ju at smc.vnet.net>...
>
>Dear mathgroup,
>
>We have just upgraded to release 3 of mathematica and we  have found a
>problem with the Expand function as described in the mathematica
>manual.  Here is the mathematica 3.0 output...
>
>
>In[3]:= Expand[Cos[x]^3 Sin[x]^2,Trig->True]
>
>gives
>
>              3       2
>Out[3]= Cos[x]  Sin[x]
>
>
>this is not the answer given in the manual, which is...
>
>  Cos[x] - Cos[3 x] - Cos[5 x]
>  ------   --------   --------
>    8         16         16
>
>
>We were led to believe that the new version was compatible with the
>previous version.
>
>Is there a switch to obtain compatibility???
>
>Any comments on this would be appreciated.  Also who should I send this
>to at Wolfram?
>
>

David,
I don't have Mathematica 2.2 anymore - can you give the reference to the
manual information that you quote please?

I also get

cs =Cos[x]^3  Sin[x]^2;
Expand[Cos[x]^3  Sin[x]^2,Trig->True]

3       2
Cos[x]  Sin[x]

But that is what I would expect.

The following two evaluations give the result that you quote from the
manual (up to multiplying out).

TrigReduce[cs]

1
-- (2 Cos[x] - Cos[3 x] - Cos[5 x])
16

Apart[cs,Trig->True]

Cos[x]   1             1
------ - -- Cos[3 x] - -- Cos[5 x]
8      16            16

----------------------
Allan Hayes
Mathematica Training and Consulting
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

```

• Prev by Date: Re: Shading Functions
• Next by Date: How to create a color contour plot with color table?
• Previous by thread: Re: Mathmatica Problem...
• Next by thread: Re: Mathmatica Problem...