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