Re: replacement x->y except in Exp[x]
- To: mathgroup at smc.vnet.net
- Subject: [mg110905] Re: replacement x->y except in Exp[x]
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Sun, 11 Jul 2010 06:18:29 -0400 (EDT)
I stand corrected. On 7/10/2010 6:23 AM, Andrzej Kozlowski wrote: > Actually I is a Symbol, before evaluation: > > In[90]:= Head[Unevaluated[I]] > > Out[90]= Symbol > > but it is no loner one after evaluation: > > In[91]:= Head[I] > > Out[91]= Complex > > Andrzej Kozlowski > > > On 10 Jul 2010, at 17:01, Murray Eisenberg wrote: > >> I is not a "symbol"! >> >> Head[I] >> Complex >> >> 3+I /. I-> -I >> 3 + I >> >> Head[2] >> Integer >> >> (2/3) /. 2->5 >> 2/3 >> >> Please stop beating the dead horse. >> >> >> On 7/8/2010 8:34 PM, AES wrote: >> >>> ...Is it ever a good idea to use ReplaceAll to do word-processing-type >>> "global find and replace" changes like this? >>> >>> Lengthy threads on this NG have pointed out the havoc that this can >>> wreak if the symbol I is among those replaced, particularly if one >>> attempts to do I -> -I. >>> >>> Or is I the _only_ symbol in the entire Mathematica vocabulary that >>> encounters this difficulty? >>> >>> (I really would like to know the answer to this question, even if this >>> is entirely out of curiosity, not any real need. I've asked it >>> previously, and never gotten an answer.) >> >> >> -- >> Murray Eisenberg murray at math.umass.edu >> Mathematics& Statistics Dept. >> Lederle Graduate Research Tower phone 413 549-1020 (H) >> University of Massachusetts 413 545-2859 (W) >> 710 North Pleasant Street fax 413 545-1801 >> Amherst, MA 01003-9305 >> > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305