Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: MATLAB modeling of finite quantum model Date: Sat, 16 Aug 2008 19:07:02 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 34 Message-ID: <g878gm$lln$1@fred.mathworks.com> References: <g85h4q$1bs$1@fred.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: webapp-02-blr.mathworks.com Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1218913622 22199 172.30.248.37 (16 Aug 2008 19:07:02 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Sat, 16 Aug 2008 19:07:02 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1187260 Xref: news.mathworks.com comp.soft-sys.matlab:485832 "Nikolaus Jewell" <nik.jewell@gmail.com> wrote in message <g85h4q$1bs $1@fred.mathworks.com>... > ...... > tan(theta) = sqrt(theta_knot^2/theta^2 - 1) > cot(theta) = -sqrt(theta_knot^2/theta^2 -1) > ....... If you are looking for real solutions and if 'sqrt' is considered non-negative, there are no solutions to your two equations! You have only to multiply the left and right sides of the equations and get the impossible equality 1 = -(sqrt(theta_knot^2/theta^2 - 1))^2 to see that. If you permit one of the above square roots to be negative, you have 1 = theta_knot^2/theta^2 - 1, which leads to tan(theta) = + or - sqrt(1) = +1 or -1. Hence theta = pi/4, 3*pi/4, 5*pi/4, or 7*pi/4. Also theta_knot = + or - theta*sqrt(2) I would suggest you look more carefully into whatever analysis went into these original two equations of yours and see if some unwarranted assumptions were made. Roger Stafford