Re: Mathmatica Problem...
- To: mathgroup at smc.vnet.net
- Subject: [mg14355] Re: [mg14320] Mathmatica Problem...
- From: David Withoff <withoff>
- Date: Thu, 15 Oct 1998 00:28:57 -0400
- Sender: owner-wri-mathgroup at wolfram.com
> 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
I am guessing that you are referring to the manual for Version 2. I
didn't see this example in the Version 3 manual, but you can get this
behavior in Version 3 using TrigReduce:
In[6]:= TrigReduce[Cos[x]^3 Sin[x]^2] //Expand
Cos[x] Cos[3 x] Cos[5 x] Out[6]= ------ - -------- -
--------
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???
There is a listing "Incompatible Changes in Version 3.0" in Appendix
A.13 of the Mathematica book, which mentions this change in the Trig
option. It is always possible to get Version 2 behavior in Version 3,
and most functionality that existed in Version 2 is identical or
closely equivalent in Version 3, but there is not a switch that will
cause Version 3 to be identical to Version 2 in every respect.
> Any comments on this would be appreciated. Also who should I send this
> to at Wolfram?
You can send technical questions, comments, suggestions, etc., to
Wolfram Research technical support at the address support at wolfram.com.
Dave Withoff
Wolfram Research