Re: Only real data

*To*: mathgroup at smc.vnet.net*Subject*: [mg122136] Re: Only real data*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Sun, 16 Oct 2011 07:06:14 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

On 10/15/11 at 6:03 AM, HB-Kowalczyk-Schroeders at t-online.de (J=C3=B6rg Schr=C3=B6der) wrote: >I have a problem to exclude complex solutions. I tried >data1={2,3/4,1.3,=E4} >{2,3/4,1.3,=E4} >Cases[data1, Except[_Complex]] >{2,3/4,1.3} >and got, what I expected. But when I have data like >{0,0,-I Sqrt[3],I Sqrt[3]} >The above doesn't work. Is this due to a different Head? Is there an >easy way to filter the non-complex data? Yes, the issue is In[21]:= Head[I Sqrt[3]] Out[21]= Times You can filter out anything with a complex value with FreeQ as follows: In[22]:= Cases[{0, 0, -I Sqrt[3], I Sqrt[3]}, _?(FreeQ[#, _Complex] &)] Out[22]= {0,0} =46reeQ[expr, pattern] returns True when any subexpression of expr matches pattern