Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: how to plot the ratio of two variables in single axis? Date: Fri, 25 Jun 2010 21:48:05 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 25 Message-ID: <i0386l$f2k$1@fred.mathworks.com> References: <1618512900.5126.1277497562574.JavaMail.root@gallium.mathforum.org> Reply-To: <HIDDEN> NNTP-Posting-Host: webapp-02-blr.mathworks.com Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1277502485 15444 172.30.248.37 (25 Jun 2010 21:48:05 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Fri, 25 Jun 2010 21:48:05 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1187260 Xref: news.mathworks.com comp.soft-sys.matlab:648130 Dinesh Kumar Kala Sekar <contactdineshraji@gmail.com> wrote in message <1618512900.5126.1277497562574.JavaMail.root@gallium.mathforum.org>... > Hi all, can anybody help me how to plot a 3d surface graph in which x axis for frequency range, y axis for ratio of two variables say Ri/Re and z axis plotted according to the formula > > omega=2*pi*f; > r = 1./(1i.*omega.*c); > z =abs(1/(1/Re + 1/( r + Ri))); > > here variable c is constant say 10. > the problem is Re and Ri should not be declared as whole value to calculate ratio between them. instead as, > > if Ri = Re then value of Ri/Re is 1 this value should be at the mid point of y axis. > > if Ri > Re then value of Ri/Re is greater than 1 this value should be at the right side from the mid point of y axis up-to certain range say, till Ri/Re = 10. > > if Ri < Re then value of Ri/Re is less than 1 this value should be at the left side from the mid point of y axis up-to certain range say, till Ri/Re = 0.1. > > please help me out if anybody knows how to solve this. it would be helpful to carry forward my project work. - - - - - - - - - - - I think you need to explain your problem with greater care and detail. As it stands, it would appear to be impossible to uniquely determine the z coordinate, knowing only the ratio Ri/Re and frequency f. That is, for a given value of Ri/Re and f, there is an infinitude of possible values for z depending on the individual values of Ri and Re with that ratio. To give you a concrete example of what I am saying, suppose that r = 3 and Ri/Re = 2. I say z is not uniquely determined. Let Ri = 2 and Re = 1 and we get z = 5/6. Yet if Ri = 4 and Re = 2, which has the same ratio, then z = 14/9. z is therefore not uniquely determined by Ri/Re and r, and there is no way to make the surface plot you are asking for. z could be any of infinitely many values for the same ratio Ri/Re. Note: I realize that your r is pure imaginary, but the above statement of non-uniqueness still holds true nevertheless. Roger Stafford