R emulation of FindRoot in Mathematica

On 19 Jan 2023, at 10:41, Troels Ring <tring at gvdnet.dk> wrote:

Hi friends - I hope this is not a misplaced question. From the literature (Kushmerick AJP 1997;272:C1739-C1747) I have a series of Mathematica equations which are solved together to yield over different pH values the concentrations of metabolites in skeletal muscle using the Mathematica function FindRoot((E1,E2...),(V2,V2..)] where E is a list of equations and V list of variables.  Most of the equations are individual binding reactions of the form 10^6.494*atp*h == hatp and next 10^9.944*hatp*h ==hhatp describing binding of singe protons or Mg or K to ATP or creatin for example, but we also have constraints giving total concentrations of say ATP i.e. ATP + ATPH, ATPH2..ATP.Mg

I have, without success, tried to find ways to do this in R - I have 36 equations on 36 variables and 8 equations on total concentrations. As far as I can see from the definition of FindRoot in Wolfram, Newton search or secant search is employed.

I'm on Windows R 4.2.2

Best wishes
Troels Ring, MD
Aalborg, Denmark