MathGroup Archive 1999

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

Search the Archive

Problem with Solve[]

  • To: mathgroup at
  • Subject: [mg20693] Problem with Solve[]
  • From: Virgil Stokes <virgil.stokes at>
  • Date: Sun, 7 Nov 1999 02:10:21 -0500
  • Sender: owner-wri-mathgroup at

First, please reply to me directly since I am unable to get any
email from the MathGroup (it appears that the MathGroup email
is not being sent properly to my server).

The problem that I have is this. Suppose I have the
two transcendental equations:

   x == l1 Cos[A] + l2 Cos[A+B]
   y == l1 Sin[A] + l2 Sin[A+B]

and I wish to solve for A,B.
I am quite sure that one set of solutions is:

  A = ArcTan[y/x] - ArcTan[(l2 Sin[B]) / (l1+l2 Cos[B])]
  B = ArcCos[(x^2 + y^2 - l1^2 - l2^2) / ( 2 l1 l2)]

This is a good solution for x,y > 0.
But, with Mathematica 3.01 I have been unable to get this solution -- what
is wrong?

--V. Stokes

  • Prev by Date: Re: $PreRead
  • Next by Date: Re: Starting values with FindRoot
  • Previous by thread: Re: Re: TensorQ
  • Next by thread: RE: Bug in math4