Andreas Varga

Small inconsistencies

3

Working with Symbolics.jl, I came accross to the following small inconsistency (see the _`true`_ value in the (1,2) element): ``` julia> F 2×2 Matrix{Num}: 0.0 1.0 -1.0 - 10.0cos(t) -24.0...

Cubic interpolation of a vector of matrices with grid/range doesn't work

9

I just started using Interpolations, being interested to interpolate time values stored in a vector of array. While linear interpolation works ``` julia> itp = LinearInterpolation([1,2,3],[rand(2,2),rand(2,2),rand(2,2)]) 3-element extrapolate(interpolate((::Vector{Int64},), ::Vector{Matrix{Float64}}, Gridded(Linear())),...

Some operations do not work although they (probably) should

4

The following code illustrates this issue: ``` M = ones(Rational,3,3) v = ones(Int,3) M*v # OK, the result is a rational vector LinearOperator(M)*v # failure ``` The execution of this...

Linear operators acting on symmetric matrices

8

I implemented several linear operators related to solve control problems. An example is the Lyapunov operator L: X -> AX+XA', where A is a squre matrix. This operator acts usually...

Matrix(op) may generate incorrect result if op * x changes x

3

`Matrix(op)` may generate incorrect result in the case when `op * x` changes the values stored in` x`. Typical example is when `op` is a linear equation solver which overwrites...

The following command produces an error ``` Fun(t->zeros(2,0),Fourier(0..pi)) ERROR: BoundsError: attempt to access 2×0 Matrix{ApproxFunBase.SumSpace{Tuple{CosSpace{PeriodicSegment{Float64}, Float64}, SinSpace{PeriodicSegment{Float64}, Float64}}, PeriodicSegment{Float64}, Float64}} at index [1] Stacktrace: [1] getindex @ .\array.jl:861 [inlined] [2]...

`f(t) = sin(2*t)` is a periodic function with period `π` but it is equally a periodic function of period `kπ`, for any integer `k`. I was courious if this is...

Some ambiguities found with Aqua

4

I tried to check my packages with [Aqua.jl](https://github.com/JuliaTesting/Aqua.jl) (just for fun). Performing the ambiguity test strictly for my package I obtained no ambiguities in my code ``` julia> Aqua.test_ambiguities(MatrixPencils,recursive=false) Test...

A bug?

6

I started some cleaning of my tests for rational transfer functions. The following fails and was commented out for `RationalTransferFunctions`. It seems however, it doesn't work for `RationalFunctions` too. ```...