Re: Avoid the use of certain functions
- To: mathgroup at smc.vnet.net
- Subject: [mg111097] Re: Avoid the use of certain functions
- From: David Bailey <dave at removedbailey.co.uk>
- Date: Tue, 20 Jul 2010 03:43:30 -0400 (EDT)
- References: <i1s6vo$a39$1@smc.vnet.net>
On 17/07/10 13:16, Sam Takoy wrote:
> Hi,
>
> Is there a way to ask Mathematica to avoid expressing answers in terms
> of certain functions. For example, I can stand Sec, Csc, Sech, and Csch
> and would rather see Sec^-1, etc.
>
> Thanks!
>
Your description is a bit confused, but I take it you would like to see
an expression output in terms of Sin rather than Csc, but the normal
evaluation process defeats you:
In[1]:= 1/Sin[x]
Out[1]= Csc[x]
One answer to this, is to make a replacement that uses your own function
- say sin[x] for which Mathematica knows nothing. So for example:
In[2]:= Csc[x]^3 /. Csc[z_] -> 1/sin[z]
Out[2]= 1/sin[x]^3
If you need to re-input such expressions, you can use another
transformation to replace sin with Sin.
BTW, if you do a lot of this sort of manipulation, it can be convenient
to collect several rules in one variable:
displayNicely={ Csc[z_] -> 1/sin[z],Sec[z_]->1/cos[z]}
Then you can just append /.displayNicely to any calculation to obtain
this effect!
David Bailey
http://www.dbaileyconsultancy.co.uk