MathGroup Archive 1999

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: 2 coupled diff. eqns

  • To: mathgroup at
  • Subject: [mg21169] Re: 2 coupled diff. eqns
  • From: Pasquale Nardone <Pasquale.Nardone at>
  • Date: Fri, 17 Dec 1999 01:22:50 -0500 (EST)
  • Organization: Brussels Free Universities VUB/ULB
  • References: <831vap$>
  • Sender: owner-wri-mathgroup at

just define
z=f+I*g then the equations reads

q=a+I*b is a complex constant
Now you go to a polar representation
you also define
q=mu*Exp[I*phi] (mu=Sqrt[a^2+b^2], and Tan[phi]=b/a, as usual)
the equations reads:
which you decompose in real and imaginary part leading to


you go then to rho versus theta (instead of rho(t) and
and the eq is:
which is integrable:

now you put rho[theta] in rho*theta'=mu*Sin[(phi-theta)] to find
the dependance of "t" versus theta to finish the problem
 Pasquale Nardone                          *
 Universite Libre de Bruxelles             *
 CP 231, Sciences-Physique-Agrigation      *
 Bld du Triomphe                           *
 1050 Bruxelles, Belgium                   *
 tel: 650,55,15 fax: 650,57,67 (+32,2)     *       *

  • Prev by Date: Re: coupled integral equations
  • Next by Date: Re: Reading data.
  • Previous by thread: 2 coupled diff. eqns
  • Next by thread: Re: 2 coupled diff. eqns