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

>>

>>

>>

>>

>

```

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