# The first column of csv must be Temp and CD.
#
Tminit <- 70
ainit <- -60
binit <- 30
asinit <- 0.1
bsinit <- 0.2
Melt.df <- read.csv(file.choose())
plot (Melt.df)
Melt.nls <- nls(CD ~ a + as*Temp + (b + bs*Temp)/(1+exp(Temp - Tm)), data=Melt.df,start=list(Tm=Tminit,a=ainit,b=binit,as=asinit,bs=bsinit))
Tm <- unname(coef(Melt.nls)["Tm"])
a <- unname(coef(Melt.nls)["a"])
b <- unname(coef(Melt.nls)["b"])
as <- unname(coef(Melt.nls)["as"])
bs <- unname(coef(Melt.nls)["bs"])
curve(a+as*x + (b + bs*x)/(1+exp(x - Tm)),min(Melt.df$Temp),max(Melt.df$Temp),add=TRUE)
mtext(paste("Tm = ",signif(Tm,digits=4),"+/-",signif(summary(Melt.nls)$parameters[1,2],digits=3)))