[R] solving system of equations involving non-linearities

[Ravi Varadhan]

You have two options:

1.  The `BBsolve' function in the "BB" package to solve this system of 3 equations.
2.  Try `nleqslv' function in the "nleqslv" package.

These would work even if the residual is not zero.

Hope this helps,
Ravi.
____________________________________________________________________

Ravi Varadhan, Ph.D.
Assistant Professor,
Division of Geriatric Medicine and Gerontology
School of Medicine
Johns Hopkins University

Ph. (410) 502-2619
email: rvaradhan at jhmi.edu


----- Original Message -----
From: Werner Wernersen <pensterfuzzer at yahoo.de>
Date: Thursday, August 6, 2009 7:56 am
Subject: [R] solving system of equations involving non-linearities
To: r-help at stat.math.ethz.ch


> Hi,
>  
>  I would appreciate if someone could help me on track with this problem.
>  
>  I want to compute some parameters from a system of equations given a 
> number of sample observations. The system looks like this:
>  
>  sum_i( A+b_i>0 & A+b_i>C+d_i) = x
>  sum_i( C+d_i>0 & C+d_i>A+b_i) = y
>  sum_i( exp(E+f_i) * ( A+b_i>0 & A+b_i>C+d_i) = z
>  
>  A, C, E are free variables while the other letters represent values 
> given from sample observations. The equations involve counts of the 
> number of fulfilled conditions and therefore non-linearities. 
> Furthermore, since I have many observations i, the equations will 
> unlikely hold exactly and solving will require some closeness measure 
> like the sum of the squared deviations or so.
>  
>  Is there any function in R suitable for solving this problem?
>  
>  Thanks so much for your help,
>    Werner
>  
>  
>  
>  
>  
>  ______________________________________________
>  R-help at r-project.org mailing list
>  
>  PLEASE do read the posting guide 
>  and provide commented, minimal, self-contained, reproducible code.