curve_fit in Optim.jl

gistfile1.txt

Optim.jl 0.4.5+ throws an error:

julia> model(x,p) = p[1].*exp(-x./p[2])+p[3]
model (generic function with 1 method)

julia> x
40-element Array{Int64,1}:
   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
 143
 144
 145
 146
 147
 148
 149
 150

julia> y
40-element Array{UInt16,1}:
 0x0d71
 0x0b49
 0x0e62
 0x0b6a
 0x0946
 0x0d4f
 0x0773
 0x083a
 0x102b
 0x0b5d
 0x0cb3
 0x0a0e
 0x0b3f
 0x0e1b
 0x0d8a
 0x0c19
 0x0b54
 0x0d3b
 0x0d92
 0x0b8a
 0x0cd0
 0x0b0e
 0x08e4
 0x0e3a
 0x0d97
 0x0b76
 0x0bac
 0x091b
 0x0b65
 0x0bd3
 0x0937
 0x0b26
 0x05dd
 0x07af
 0x056d
 0x061b
 0x07a2
 0x0541
 0x05fb
 0x047e

julia> p
3-element Array{Float64,1}:
 2291.0
  150.0
 1150.0

julia> curve_fit(model,x,y,p)
ERROR: Base.LinAlg.SingularException(3)
 in \ at linalg/factorization.jl:25
 in \ at linalg/dense.jl:448
 in levenberg_marquardt at /home/arthurb/.julia/v0.4/Optim/src/levenberg_marquardt.jl:84
 in lmfit at /home/arthurb/.julia/v0.4/LsqFit/src/curve_fit.jl:29
 in curve_fit at /home/arthurb/.julia/v0.4/LsqFit/src/curve_fit.jl:39