Re: Equations over Domains with Mathematica 4?
- To: mathgroup at smc.vnet.net
- Subject: [mg103070] Re: Equations over Domains with Mathematica 4?
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Mon, 7 Sep 2009 02:34:10 -0400 (EDT)
- References: <h80705$18i$1@smc.vnet.net>
On 2009.09.06. 13:38, Martin Harborth wrote: > For the following equation, I want to get only the solutions > for z where z is real: > > Reduce[13219.56 == 20000/1.95583 * (1 + z)^11, z] > > It is suggested that one uses > > Reduce[13219.56 == 20000/1.95583 * (1 + z)^11, z, Reals] > > But I use Mathematica 4 and it seems that Reduce does not have > this option in this Mathematica version. > > Can I anyway constrain the solution space with Mathematica 4? Since you have a polynomial equation with inexact coefficients, I suggest using NSolve, and filtering out the non-real solutions in the end. I cannot test it in Mathematica 4, but I believe this will work: Select[z /. NSolve[13219.56 == 20000/1.95583*(1 + z)^11, z], Im[#] == 0 &]