Solving equations
- To: mathgroup at smc.vnet.net
- Subject: [mg17104] Solving equations
- From: "Marcos Duarte" <mxd47 at psu.edu>
- Date: Sat, 17 Apr 1999 03:35:04 -0400
- Organization: Penn State University, Center for Academic Computing
- Sender: owner-wri-mathgroup at wolfram.com
I'm trying to solve the following equations in Mathematica to find a solution for a2 and a1: x=d1*Cos[a1]+d2*Cos[a1+a2] y=d1*Sin[a1]+d2*Sin[a1+a2] These equations express the end-point position (x,y) of a two-link arm for a planar case. The answer (which are the angles (a1,a2) for a given (x,y)) is straightforward: a2=ArcCos[(x^2+y^2-d1^2-d2^2)/(2*d1*d2)] a1=ArcTan[y/x]-ArcTan[(d2*Sin[a2])/(d1+d2*Cos[a2])] But M. gets lost with all possible values that x,y,d1, and d2 can assume and because of the use of inverse functions. I also imposed the constraint that all the 4 parameters are different from zero, but still I don't get anything close to the answer given above. Does anybody have a solution? Thanks in advance. -- Marcos Duarte Biomechanics Lab Pennsylvania State University 39 Rec. Building University Park, PA 16801 Tel: 814 8653445 Fax: 814 8652440 Home: 814 8616157