Re: extract from Reduce

*To*: mathgroup at smc.vnet.net*Subject*: [mg130361] Re: extract from Reduce*From*: Peter Pein <petsie at dordos.net>*Date*: Thu, 4 Apr 2013 22:32:36 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <kjkc5k$7n0$1@smc.vnet.net>

Am 04.04.2013 19:10, schrieb hamiltoncycle at gmail.com: > I have a result from the command Reduce that looks like this (as an example): > > a:= x==3||x==4||x==7 > > I need to extract the numbers but I can't find a nice way to handle the case when there is only one equation, for instance: > > a:= x==6 > > currently I check what the head of the expression is (Head[a]) and handle the case Head[a]=Or with a Map[] and the case Head[a]="Equal" with a[[2]]. Not very nice, but I guess that there is a neat way to do it. > > cheers, Robert > Hi Robert, say you've got a quite simple result of Reduce: In[1]:= InputForm[a = Reduce[Mod[x, 3] == Mod[1 + x^2, 5], x, Integers]] Out[1]//InputForm= Element[C[1], Integers] && (x == 3 + 15*C[1] || x == 10 + 15*C[1] || x == 11 + 15*C[1] || x == 12 + 15*C[1] || x == 14 + 15*C[1]) then In[2]:= Cases[LogicalExpand[a] /. And | Or -> List, HoldPattern[Equal[v___, x, w___]] :> Sequence[v, w], Infinity] // InputForm Out[2]//InputForm= {3 + 15*C[1], 10 + 15*C[1], 11 + 15*C[1], 12 + 15*C[1], 14 + 15*C[1]} in your even simpler case a= x==3||x==4||x==7 Refine[x, #]& /@ List @@ a would be sufficient to get {3, 4, 7} hth, Peter