Folks; I have looked for this subject extensively using all the resources I
have available and could not find a solution; therefore I am sending you this
email seeking for help. I need to solve a discontinuous nonlinear function, but
R 2.6 keeps giving me an error. Below is a simple example:
f <- function (t,k,l,u) { r0<-346.1 x<-t-l if (x<0) r0 else
(r0-u)*exp(-k*x)+u }prof1<-read.table("c:\\data.txt",
header=TRUE)results<-nls(y1~f1(t,k,l,u), data=prof1, start=list(k=0.05, l=4,
u=154))
Errors I am getting are:
Error in qr(.swts * attr(rhs, "gradient")) : dims [product 3] do not match
the length of object [10]In addition: Warning messages:1: In if (x < 0) r0 else
(r0 - u) * exp(-k * x) + u : the condition has length > 1 and only the first
element will be used2: In if (x < 0) r0 else (r0 - u) * exp(-k * x) + u : the
condition has length > 1 and only the first element will be used3: In if (x <
0) r0 else (r0 - u) * exp(-k * x) + u : the condition has length > 1 and only
the first element will be used4: In if (x < 0) r0 else (r0 - u) * exp(-k * x) +
u : the condition has length > 1 and only the first element will be used5: In
if (x < 0) r0 else (r0 - u) * exp(-k * x) + u : the condition has length > 1
and only the first element will be used6: In .swts * attr(rhs, "gradient") :
longer object length is not a multiple of shorter object length
Data file is this one
t y1
1 0 346.12 3 343.13 6 327.44 12 280.95 18 242.76 24 228.67 36 193.48
48 174.29 72 164.810 96 152.0
Any help?
Thanks a lot
Luis
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