Re: Diff. Equ

*To*: mathgroup at smc.vnet.net*Subject*: [mg43748] Re: Diff. Equ*From*: "Peter Pein" <nospam at spam.no>*Date*: Fri, 3 Oct 2003 02:28:38 -0400 (EDT)*References*: <blcq7i$p63$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Add the condition ;/NumericQ[thetastrich] at the end of the definition of SolutionFind. You'll probably have to do the same at the definitions of R and Teta: SolutionFind[druck_, v_, tetastrich_] := With[...]/;NumericQ[tetastrich] This should work fine. -- Peter Pein, Berlin peer.pien at freenet.de please correct my name to write to me! "Prechtl Josef" <e9426270 at stud4.tuwien.ac.at> schrieb im Newsbeitrag news:blcq7i$p63$1 at smc.vnet.net... > Hello, > I'm trying to solve a set of ordinary diff. equations (the independant > parameter is s), for which certain boundary conditions have to be > fulfilled: one boundary condition at s=0, the second one at an unknown s1. > I am trying to solve this equation with a 'shooting' method, trying to > vary one parameter (in my case it is tetastrich) in the system of diff. > equation, and have a look if the boundary equations are fulfilled at the > second boundary. This is implemented in Solution[] via FindRoot. > SolutionFind[..,tetastrich] should solve the diff. equation for a given > tetastrich (basically it uses NDSolve[]). Obviously, in order to do that, > this routine needs to be evaluated already with a certain numerical value > of tetastrich; however, in my case this seems not to be the case, since I > always get the error message: > NDSolve::"ndinn": "Initial condition \!\(1.`\\ tetastrich\) is not a > number." > > WHY?????????? > Thanx for any useful comment in advance!! > j.h. > > > Solution[druck_, v_] := > FindRoot[Evaluate[SolutionFind[druck, v, tetastrich]], {tetastrich, 0}] > > SolutionFind[druck_, v_, tetastrich_] := > With[{min = > FindMinimum[ > Evaluate[-Teta[s, druck, v, tetastrich]], {s, 0, 0, > 2\[Pi]}][[2]]}, {R[s, druck, v, tetastrich] == 0 /. min, > Teta[s, druck, v, tetastrich] == \[Pi] /. min}] >