Displaying 2 results from an estimated 2 matches for "gstar".
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gstat
2009 Apr 23
2
Two 3D cones in one graph
...-2*g$x*mu[1]/a**2+2*g$y*mu[2]/b**2
p2<-(g$x**2/a**2+g$y**2/b**2)
p3<-mu[1]**2/a**2+mu[2]**2/b**2-1
q<-(p1+sqrt(p1**2-4*p2*p3))/(2*p2)
z<-sqrt(1-(q*g$x)**2-(q*g$y)**2)
zstar<-(z/q)
ind0<-!(q<1)
g$z<-zstar
sc<-matrix(c(rep(c(-1,-1,-1),sum(ind0))),nrow=sum(ind0),byrow=TRUE)
gstar<-rbind(g[ind0,],sc*g[ind0,])
group<-c(rep(1,nrow(gstar)/2),rep(2,nrow(gstar)/2))
gstar$group<-group
wireframe(z~x*y|group,gstar,colorkey=TRUE,drape=TRUE,
scales=list(arrows=FALSE))
2011 Sep 19
0
nls picewise FvCB model
...GE<-data.frame( Ci<-c(81,87,91,111,159,173,295,453,629,984),
A<-c(-0.9,1.2,3.5,8.3,13.1,14.4,22.9,27.3,29.6,32.6) )
rhs <- function(Ci, Vcmax, J, Rd) {
? ?R <-0.008314472
? ?Tleaf <-25
? ?Kc <-exp(38.05-79.43/(R*(Tleaf+273.15)))
? ?Ko <-exp(20.30-36.38/(R*(Tleaf+273.15)))
? ?Gstar <-exp(19.02-38.83/(R*(Tleaf+273.15)))
? ?O <-210
? ?ge<-min( ?(Vcmax*(Ci-Gstar))/(Ci+(Kc*(1+(O/Ko))))
,(J*(Ci-Gstar))/((4*Ci)+(8*Gstar)) ?) -Rd
? ?ge
? ?}
m<- nls(A ~ rhs(Ci, Vcmax, J, Rd), data=GE, start = list(Vcmax=50,
J=150, Rd=4), trace = T)
And get the following error:
Error in...