Dear All,
I have to fit the following model to growth data of Hevea (rubber) trees: *a=a-(a-b)exp(-(2/p)(F(t)-F(t0))).* Where *F(t)=t+(A/2pi)(sin 2pi(t-t1))*, *F(t0)=t0+(A/2pi)(sin 2pi(t0-t1)), t1* signifies the maximum point of *f(t)*. Thus the equation becomes: *a=a-(a-b)exp(-(2/p)(t+(A/2pi)(sin 2pi(t-t1)))- (t0+(A/2pi)(sin 2pi(t0-t1))))* Up to this step, I have succeeded very well. *My problem is with the following model for which I need help. * The same equation is further developed into a seasonal cessation model by deriving equivalent equations to replace *F(t)*. For the purpose of seasonal cessation model *F(t)* is derived as: * n(1-T)+S(t-n) (n<=t<n+t2), * *F(t) = n(1-T)+S(t2) (n+t2<=t<n+t3), * * n(1-T)+S(t-n-T) (n+t3<=t<n+1),* where *S(t)=t+((1-T)/(2pi))(sin 2pi((t-t1)/(1-T))),* n=integral part of t, *t2=t1+(1-T)/2, t3=t1+(1+T)/2 , T=no growth period. *Similarly the above equations have to be modified *for F(to).* These have to be integrated in to: *a=a-(a-b)exp(-(2/p)(F(t)-F(t0))).* Kindly help with a suitable code to fit the above model to my data. References: 1. Akamine, T (1993). A New Standard Formula for Seasonal Growth of Fish in Population Dynamics. Nippon Suisan Gakkaishi 59(11):1857-1863. 2. Akamine, T (2009). Non-linear and graphical methods for fish stock analysis with statistical modelling. Aqua-BioScience Monographs VOL. 2 NO. 3 :1-45. -- Dr. TR Chandrasekhar, M.Sc., M. Tech., Ph. D., Sr. Scientist Rubber Research Institute of India Hevea Breeding Sub Station Kadaba - 574 221 DK Dt., Karnataka Phone-Land: 08251-214336 Mobile: 9448780118 [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology