Dear All,

My aim is to fit some real data with a pretty complex curve representing a superposition of dumping, oscillating and other simple ‘sub-curves’. I use LsqFit. Here is the code example:

```
using LsqFit
model(t, p) = p[1] * exp.(-p[2] * t)
model1(t, p) = p[1] * exp.(-p[2] * t) + p[3] * exp.(-p[4] * t) * cos.(p[5] * t + p[6])
# x data
tdata = range(0,stop=10,length=20)
# func data
ydata = model(tdata, [1.0 2.0]) + 0.01*randn(length(tdata))
p0 = [0.5, 0.5 ,0.5, 0.5, 0.5, 0.5]
fit = curve_fit(model1, tdata, ydata, p0)
param = fit.param
```

The example with model works just fine, but if now change it to something i want, e.g., model1 - i get something like this:

```
julia> fit = curve_fit(model1, tdata, ydata, p0)
ERROR: MethodError: no method matching +(::Array{Float64,1}, ::Float64)
Closest candidates are:
+(::Any, ::Any, ::Any, ::Any...) at operators.jl:502
+(::Bool, ::T<:AbstractFloat) where T<:AbstractFloat at bool.jl:112
+(::Float64, ::Float64) at float.jl:395
```

Many thanks in advance for any tips/solutions!