Re: Real Solutions

*To*: mathgroup at smc.vnet.net*Subject*: [mg95830] Re: Real Solutions*From*: dimitris <dimmechan at yahoo.com>*Date*: Wed, 28 Jan 2009 06:31:19 -0500 (EST)*References*: <glmssi$mkr$1@smc.vnet.net>

On 27 =CE=99=CE=B1=CE=BD, 13:58, Kowalczyk-Schr=C3=B6der wrote: > Hi, > I need only the real solutions from Solve or NSolve. I found a > complicated way with a lot of "ifs" to get, what I want. Is there an > easier way to do this? (I don't want to use Reduce.) > Regards > J.Schroeder Something like In[75]:= x /. Solve[x^4 + x^3 + x^2 + 2*x + 1 == 0, x] Select[%,Element[#,Reals] & ] Out[75]= {-1, -(2/(3*(-9 + Sqrt[93])))^(1/3) + ((1/2)*(-9 + Sqrt[93]))^(1/3)/3^ (2/3), -(((1 + I*Sqrt[3])*((1/2)*(-9 + Sqrt[93]))^(1/3))/(2*3^(2/3))) + (1 - I*Sqrt[3])/(2^(2/3)*(3*(-9 + Sqrt[93]))^(1/3)), -(((1 - I*Sqrt[3])*((1/2)*(-9 + Sqrt[93]))^(1/3))/(2*3^(2/3))) + (1 + I*Sqrt[3])/(2^(2/3)*(3*(-9 + Sqrt[93]))^(1/3))} Out[76]= {-1, -(2/(3*(-9 + Sqrt[93])))^(1/3) + ((1/2)*(-9 + Sqrt[93]))^(1/3)/3^ (2/3)}