Notify user what vector/matrix size is expected for x0, u

[mzaffalon]

No description provided.

[mzaffalon]

Replaces #761

Also, when u0 is a scalar, there is the error message reported here: #761 (comment).

One question: I see that u is defined to be an AbstractVecOrMat, but shouldn't u be a vector when there is explicit time dependence and a matrix otherwise? The same holds for x0.

One last thing: some files do not have a newline after the last line and Emacs works very hard to add one: sorry if such a change escaped my attention.

[codecov]

Codecov Report

Merging #768 (c568888) into master (e82df22) will increase coverage by 0.67%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #768      +/-   ##
==========================================
+ Coverage   94.57%   95.25%   +0.67%     
==========================================
  Files           4        4              
  Lines         295      295              
==========================================
+ Hits          279      281       +2     
+ Misses         16       14       -2     

Impacted Files	Coverage Δ
src/timeresp.jl	94.93% <66.66%> (+0.92%)	⬆️

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[baggepinnen]

For this method, u should always have time in the second dimension, we allow AbstractVectOrMat simply to be able to provide the error message for a vector telling the user what size of u is expected.

One last thing: some files do not have a newline after the last line and Emacs works very hard to add one: sorry if such a change escaped my attention.

Adding this newline is much less problematic since it doesn't change any existing code, so don't worry about hem :)

[baggepinnen]

Thanks for fixing up the PR, and also for fixing some of the docs :)

[mzaffalon]

For this method, u should always have time in the second dimension, we allow AbstractVectOrMat simply to be able to provide the error message for a vector telling the user what size of u is expected.

I assume you mean for discrete systems: continuous systems need a function that returns a vector with dimention nu. I was speaking about continuous systems, in particular https://github.com/JuliaControl/ControlSystems.jl/blob/master/src/timeresp.jl#L29. Would it not be easier to impose u be just a vector?

Why is x0 initialized with zeros(Bool)?

[baggepinnen]

Would it not be easier to impose u be just a vector?

If it solves #769 then sure, sounds like a good idea.

Why is x0 initialized with zeros(Bool)?

To make sure we do not accidentally promote the state to a larger type than what is used for the system parameters. Nowadays we have ControlSystemsBase.numeric_type which could be used to initialize x0 instead.