Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: search for an operator in an expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg78281] Re: search for an operator in an expression
  • From: dh <dh at metrohm.ch>
  • Date: Wed, 27 Jun 2007 05:34:51 -0400 (EDT)
  • References: <f5iuqu$a99$1@smc.vnet.net> <f5o8jr$5jo$1@smc.vnet.net> <f5qhdc$2jt$1@smc.vnet.net>


Hi,

you must distinguish between OutputFormat, what you see, and FullForm, 

what Mathematica sees. Try: FullForm[yourExpression] then you will see 

that you have 1 operator Plus with multiple arguments. If you want to 

see the number of arguments, you could e.g. use:

Cases[expression, Plus[x__] :> Length[x]]

hope this helps, Daniel



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.

> 

> dh wrote:

> 

>> Hi Daniel,

>>

>> you may use "Count". Take care to search on all "levels" and prevent 

>>

>> evaluation of the operator. Asssuming your expression is in: expr, e.g.:

>>

>> Count[expr, HoldPattern[ Plus[__] ], Infinity]

>>

>> hope this helps, Daniel

>>

>>

>>

>>

>>

>> Daniel wrote:

>>

>>

>>> Is there a way to search for an operator in a symbolic expression? My wish is to show that there is only "+" in a very large expression. Rather than showing an expression on multiple pages I would like to perform a search that shows there is only "+" between the terms. Converting to a string does not seem to work since the expression is written on multiple lines(fractions, exponents etc..)

>>

>>

>>> Thanks

>>

>>

>>

>>

> 




  • Prev by Date: Second argument of BeginPackage, revisited
  • Next by Date: Re: Re: problem with Pick
  • Previous by thread: Re: search for an operator in an expression
  • Next by thread: Re: search for an operator in an expression