FindRoot with complex roots
- To: mathgroup at smc.vnet.net
- Subject: [mg9694] FindRoot with complex roots
- From: hines <hines at drea.dnd.ca>
- Date: Fri, 21 Nov 1997 01:31:31 -0500
- Organization: A poorly-installed InterNetNews site
- Sender: owner-wri-mathgroup at wolfram.com
Dear Newsgroup I've been having trouble with the FindRoot function when the root(s) is complex. One such function is: r*Cos[x]+zs*Sin[x]-zwCos[x]Sin[x]/Sqrt[n^2-Sin^2[x]]=0 where r,zs,zw are real and zs<0, and n complex. Typical values are r=100,zs=-10, and zw=20, n=1.0067+0.01I. When I use the substitution Sin[x]=y, Cos[x]=Sqrt[1-y^2] FindRoot works fine. When I try and solve it in trig expressions, it gives me errors like "Function... is not a length 1 list of numbers at x= .789...-.00123I" The FindRoot function handles the trig forms just fine when I set n = a purely real number and the root(s) are real. Paul Hines