Tianyi Pu

## Details ```julia plot(1:5,1:5,1:5, xlims=(1,5), ylims=(1,5), zlims=(1,5), framestyle=:box,foreground_color_grid=:red, gridalpha=1, thickness_scaling=5, color=:transparent) ``` on pgfplotsx():  ### Backends This bug occurs on ( insert `x` below ) Backend | yes |...

```jldoctest julia> f=Fun(JacobiWeight(2.0,0.0,Jacobi(2.0,-2.0)),[0,1.0]); julia> plot(x->f(x),xlims=(-1,1)) ```  ```jldoctest julia> plot(f) ```  You may change `JacobiWeight(2.0,0.0,Jacobi(2.0,-2.0)` to `Jacobi(2.0,-2.0)` and the results are still different.

I once planned to add this post to documentations, but some of these tips are workarounds for bugs which I have encountered and can be fixed at any time so...

Fun(function,Legendre(BigFloat interval)) never returns

1

```Julia > using ApproxFun > @time Fun(BigFloat(1),Legendre()) 0.000463 seconds (316 allocations: 23.984 KiB) Fun(Legendre(),BigFloat[1.0]) > @time Fun(1,Chebyshev(BigFloat(-1)..1)) 0.000060 seconds (31 allocations: 1.125 KiB) Fun(Chebyshev(-1.0..1.0),BigFloat[1.0]) > @time Fun(1,Legendre(BigFloat(-1)..1)) never returns ```

erfcx(BigFloat) misses a connection segment

5

```julia Plots.plot(20000:40000,erfcx.(BigFloat(20000):40000), yaxis=:log) ``` 

`one(::Eye)` should return `Eye`

2

```julia julia> one(Eye(∞)) ERROR: ArgumentError: Cannot fill! with 1.0 an AbstractFill with value 0.0. Stacktrace: [1] fill! at C:\Users\DELL\.julia\packages\FillArrays\tE9Xq\src\FillArrays.jl:52 [inlined] [2] fill! at C:\Users\DELL\.julia\packages\LazyArrays\DfNL4\src\cache.jl:309 [inlined] [3] one(::Diagonal{Float64,Ones{Float64,1,Tuple{InfiniteArrays.OneToInf{Int64}}}}) at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\LinearAlgebra\src\special.jl:305 [4]...

StackOverFlow Error

4

```julia julia> A=BlockBandedMatrix(Zeros(1,1),[1],[1],(0,0)) 1×1-blocked 1×1 BlockSkylineMatrix{Float64,Array{Float64,1},BlockBandedMatrices.BlockSkylineSizes{Tuple{BlockedUnitRange{Array{Int64,1}},BlockedUnitRange{Array{Int64,1}}},Fill{Int64,1,Tuple{Base.OneTo{Int64}}},Fill{Int64,1,Tuple{Base.OneTo{Int64}}},BandedMatrices.BandedMatrix{Int64,Array{Int64,2},Base.OneTo{Int64}},Array{Int64,1}}}: 0.0 julia> A[Block(1)] ERROR: StackOverflowError: Stacktrace: [1] view(::BlockSkylineMatrix{Float64,Array{Float64,1},BlockBandedMatrices.BlockSkylineSizes{Tuple{BlockedUnitRange{Array{Int64,1}},BlockedUnitRange{Array{Int64,1}}},Fill{Int64,1,Tuple{Base.OneTo{Int64}}},Fill{Int64,1,Tuple{Base.OneTo{Int64}}},BandedMatrices.BandedMatrix{Int64,Array{Int64,2},Base.OneTo{Int64}},Array{Int64,1}}}, ::Block{1,Int64}) at C:\Users\pty\.julia\packages\BlockArrays\g01fJ\src\abstractblockarray.jl:129 (repeats 79984 times) ``` An error is expected, but not stack overflow maybe?

StackOverflowError: infinite call loop between LazyArrays and ArrayLayouts

2

```julia julia> A = zeros(1,1) * BandedMatrix(0=>Zeros(∞))[1:1,1:1] * zeros(1,1) (1×1 Array{Float64,2}) * (1×1 BandedMatrix{Float64} with bandwidths (0, 0) with data (1×0 view(::Array{Float64,2}, 1:1, 1:0) with eltype Float64) * (0×1 view(::LazyArrays.ApplyArray{Float64,2,typeof(vcat),Tuple{Zeros{Float64,2,Tuple{Base.OneTo{Int64},InfiniteArrays.OneToInf{Int64}}}}},...

Can't do BandedMatrix{BigFloat} \ Vector

3

```Julia >B=BandedMatrix{BigFloat}(ones(3,3), (0,0)) 3×3 BandedMatrix{BigFloat,Array{BigFloat,2},Base.OneTo{Int64}}: 1.0 ⋅ ⋅ ⋅ 1.0 ⋅ ⋅ ⋅ 1.0 > b=BigFloat[1,2,3] 3-element Array{BigFloat,1}: 1.0 2.0 3.0 > B\b UndefVarError: banded_lufact! not defined Stacktrace: [1] #lu!#18(::Bool,...

implement `mapreduce(f, op)` without any collection input for disambiguity

2

Although unintended (I guess), currently `mapreduce(f, op)` can work, returning `f()`. However this can easily cause ambiguity if `mapreduce` tries to support custom types. For example, ```julia julia> mapreduce(eps, +)...