I have tried hard to write a minimalist sample code of the situation I am facing,

but fail :-(.

Part of my data is stored in a MAT-file (generated by Julia package MAT).

After reading back the vector `eis_frequency_Shunt`

which is nested inside this MAT,

the result is of type `Vector(Any)`

. In the next step I take out one element of the

vector and the result is again a vector (`Vector{Any}`

), holding one element.

Now it happens that the function that takes this one-element vector fails to execute,

because the compiler complains about a format mismatch (see below).

I had to use the notation `[]`

to make it possible to run my script,

the annoying thing was, it took a while for me, to figure out the root-cause of the

crash.

Here a snippet of my code:

```
[...]
_frequ_Shunt = eis_frequency_Shunt[indx_in_FFT_results]
_A, _B = MyLibCalibrationAmplPhase(_frequ_Shunt, B, C, D, E)
```

And here the definition of the function:

```
function MyLibCalibrationAmplPhase(_frequency::Real, _data_pts::Vector{<:Number},
_sampl_rate::Real, _num_periods::Int=10, _LSQ_method::Int=0)
[...]
end
```

And here the error message (the first two lines are debugging output):

```
DBG: _frequ_Shunt, type: Vector{Any}, size: (1,)
DBG: eis_frequency_Shunt, type: Vector{Any}, size: (46,)
[...]
ERROR: MethodError: no method matching MyLibCalibrationAmplPhase(::Vector{Any}, ::Vector{Float64}, ::Float64, ::Int64, ::Int64)
Closest candidates are:
MyLibCalibrationAmplPhase(::Real, ::Vector{<:Number}, ::Real, ::Int64, ::Int64) at C:\data\git_repos\hycenta_julia\Julia_Modules\SignalAnalysis\HyCentaHarmonicSignalAnalysis.jl:148
MyLibCalibrationAmplPhase(::Real, ::Vector{<:Number}, ::Real, ::Int64) at C:\data\git_repos\hycenta_julia\Julia_Modules\SignalAnalysis\HyCentaHarmonicSignalAnalysis.jl:148
MyLibCalibrationAmplPhase(::Real, ::Vector{<:Number}, ::Real) at C:\data\git_repos\hycenta_julia\Julia_Modules\SignalAnalysis\HyCentaHarmonicSignalAnalysis.jl:148
```

I can avoid this error by adding empty squared brackets: `[]`

:

```
_frequ_Shunt = eis_frequency_Shunt[indx_in_FFT_results][]
```

This was the trigger to think about, how to improve my function,

to handle this strange situation.