Re: search for an operator in an expression
- To: mathgroup at smc.vnet.net
- Subject: [mg78283] Re: search for an operator in an expression
- From: Bill Rowe <readnewsciv at sbcglobal.net>
- Date: Wed, 27 Jun 2007 05:35:52 -0400 (EDT)
On 6/26/07 at 4:05 AM, josh2499 at hotmail.com (rob) wrote: >Sir, I tried your suggestion as follows: >expr = 2 + a*Exp[-b x] + Sin[c + b] + d >Count[expr, HoldPattern[Plus[__]], Infinity] >which gives a result of "1". I count 4 "+" in expr. Please, what am >I doing wrong? Thanks. =46irst, there are not 4 Plus operators in your expression as can be seen from FullForm In[29]:= FullForm[expr] Out[30]//FullForm= \ Plus[2,d,Times[a,Power[E,Times[-1,b,x]]],Sin[Plus[b,c]]] I don't understand why the code above returns 1 instead of 2, but this seems to work correctly. In[[30]]:= Count[FullForm@expr, _Plus, Infinity] Out[[30]]= 2 I note your expression is the sum of 4 terms. Perhaps what you really want is the number of terms in your expression rather than the number of times Plus occurs. If so, that can be obtained with In[31]:= Length[List @@ expr] Out[31]= 4 -- To reply via email subtract one hundred and four