Path: news.mathworks.com!not-for-mail From: "Dinesh " <revooridinesh@gmail.com> Newsgroups: comp.soft-sys.matlab Subject: Re: HOw to solve these type of equations Date: Sun, 5 Aug 2012 01:38:17 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 22 Message-ID: <jvkiq9$ipf$1@newscl01ah.mathworks.com> References: <jvj241$86u$1@newscl01ah.mathworks.com> <e987e179-57a8-4cc1-a136-fd2fb87df383@u17g2000yqa.googlegroups.com> Reply-To: "Dinesh " <revooridinesh@gmail.com> NNTP-Posting-Host: www-02-blr.mathworks.com Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: newscl01ah.mathworks.com 1344130697 19247 172.30.248.47 (5 Aug 2012 01:38:17 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Sun, 5 Aug 2012 01:38:17 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 3593378 Xref: news.mathworks.com comp.soft-sys.matlab:775684 > if no y3' then it not differential equation but algebra like in > school. just move the known to the left and unknown to the right to > solve and for the first 2 differentials use the matlab od54 functions > but need initial conditions Thank you for the reply the three equations are functions of y1,y2,y3 and i know the values before time 0- my original equations are C1*y1' = F*C2*y2 - C3*y1 y2' = C4 -B* C5*y3 - C6*y1 y2-C7=x(t)*y3 X(t) is a known function where F = 0 when y3<y1 1 when y3>y1 B=0 when C7<y3 1 when C7>y3 so what I am thinking is at time t1 i will get the values for F and B depending on previous values and X value will be known and I need the solution for the unknowns at time t1. I tried solving this by newton raphshon method but the solution is not converging. Thanks a lot