Re: Built-In fuctions redefined---How?
- To: mathgroup at smc.vnet.net
- Subject: [mg62624] Re: Built-In fuctions redefined---How?
- From: Peter Pein <petsie at dordos.net>
- Date: Tue, 29 Nov 2005 06:43:40 -0500 (EST)
- References: <dmh92m$8rj$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Virgil Stokes schrieb: > How can I introduce the following definitions: > > cx for Cos[x] > sx for Sin[x] > > where, the argument x, will always be a single symbol, and then still be > able to use the trigonometric identities associated with Sin, Cos; e.g., > > cx^2 + sx^2 = 1 > > Note, this is not c x (3 symbol expression); but, cx (2 symbol > expression). > Why? Because I have some rather large matrices with many elements that > contain expressions in Cos and Sin terms that make printing and > displaying messy and using the MatrixForm can give truncation in the > printed output. > > --V. Stokes > > > Hi! Use Format: In[1]:= Unprotect[Cos, Sin]; Format[Cos[x_] := "c" <> ToString[x]]; Format[Sin[x_] := "s" <> ToString[x]]; In[4]:= Expand[(Cos[x] + Sin[t])^3] Out[4]= "cx"^3 + 3*"cx"^2*"st" + 3*"cx"*"st"^2 + "st"^3 In[5]:= TrigExpand[% /. t -> x] Out[5]= 1 + 2*"cx"*"sx" Peter