Re: Can someone explain this?

*To*: mathgroup at smc.vnet.net*Subject*: [mg19150] Re: Can someone explain this?*From*: Bruno Daniel <bruno.daniel at hadiko.de>*Date*: Thu, 5 Aug 1999 23:58:51 -0400*Organization*: University of Karlsruhe*References*: <7obcl4$3te@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi Benjamin Sin[x]/Cos[x] is simplified to Tan[x] whenever it occurs in an expression. You can prevent this by wrapping it with HoldForm: In[1]:= x y Tan[x] + Tan[y] /. Tan[z_]->HoldForm[Sin[z]/Cos[z]] Out[1]= x y Sin[x] / Cos[x] + Sin[y] / Cos[y] The expression Sin[x] / Cos[x] is then kept because it is in the Hold status. You can release all holds in an expression with ReleaseHold: In[2]:= % // ReleaseHold Out[2] = x y Tan[x] + Tan[y] Yourse sincerely Bruno