Re: RE: question on changing 'type' of numbers

*To*: mathgroup at smc.vnet.net*Subject*: [mg69550] Re: [mg69495] RE: [mg69473] question on changing 'type' of numbers*From*: Sseziwa Mukasa <mukasa at jeol.com>*Date*: Fri, 15 Sep 2006 06:45:36 -0400 (EDT)*References*: <200609141055.GAA21466@smc.vnet.net>

On Sep 14, 2006, at 6:55 AM, David Park wrote: > However, there seem to be cases where this is only partly true. For > example > with complex numbers... > > AtomQ[2 + 3 I] > True > > We can't change the Head > > Head[List @@ (2 + 3 I)] > Complex > > but we can certainly access the parts > > 2 + I 3 /. Complex[a_, b_] -> {a, b} > {2, 3} > > Maybe others will point out other 'in between' objects. I think this is a side effect of how different atoms are represented. FullForm[9] is 9 but FullForm[9+I] is Complex[9,1], so the pattern Complex[a_,b_] will match a complex number but Integer [x_] will not match an integer. I'm too lazy to search for atoms whose FullForm contains a pattern that I can match to, but that would be the strategy for finding 'in between' objects. Incidentally though there's no fundamental difference between 2 + I 3 /. Complex[a_, b_] -> {a, b} and 9/.x_->{x,x} the head isn't actually changing in either case. Regards, Ssezi

**References**:**RE: question on changing 'type' of numbers***From:*"David Park" <djmp@earthlink.net>