Re: Domain of a function
- To: mathgroup at smc.vnet.net
- Subject: [mg122857] Re: Domain of a function
- From: Peter Pein <petsie at dordos.net>
- Date: Sat, 12 Nov 2011 07:36:22 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <j9b6lb$4sv$1@smc.vnet.net>
Am 08.11.2011 13:17, schrieb Tutor: > Hallo! > > How can I find the domain of a function? > > something like this: ForAll[Element[f,Reals]] and it should return > something like this: x element ]-2,oo[ > > I have NO idea, how this can be done for a function f... > With a little luck, Reduce can do this: In[20]:= Reduce[Element[x | Sqrt[2 + x], Reals], x] Out[20]= x >= -2 In[21]:= Reduce[Element[x | Sqrt[1/2 + Sin[x]], Reals, x, Reals] Out[21]= (Element[C[1], Integers] && (x == -Pi/6 + 2 Pi C[1] || x== 7 Pi/6 + 2 Pi C[1])) || (Element[C[1], Integers] && 1/6 (-Pi + 12 Pi C[1]) < x < 1/6 (7 Pi + 12 Pi C[1]))