commit 1a0251ce5251d67594e5da82ad048ac12aa558e2
Author: Jonas Hahn <jonas@hahn1.one>
Date:   Mon Jan 19 23:30:03 2026 +0100

    Add simple julia script for ML testing and polynominal calc

diff --git a/WitjesHahnZettel5.5.jl b/WitjesHahnZettel5.5.jl
new file mode 100644
index 0000000..56c325a
--- /dev/null
+++ b/WitjesHahnZettel5.5.jl
@@ -0,0 +1,315 @@
+import Pkg
+try
+    using Plots
+    using Flux
+    using Flux: train!
+catch
+    Pkg.add("Plots")
+    Pkg.add("Flux")
+
+    using Flux
+    using Flux: train!
+    using Plots
+end
+
+using Statistics
+using Random
+using Base.Iterators: flatten
+
+gr()
+
+"""
+Das Programm kann mit
+julia -i WitjesHahnZettel5.5.jl
+gestartet werden. Dazu muss https://julialang.org/ (am besten v1.10) installiert sein.
+
+Der interaktive Teil wird mit
+julia
+include("WitjesHahnZettel5.5.jl")
+inter()
+gestartet. Fuer den ML Teil kann f() ausgefuehrt werden.
+
+Beispielhafte Programmausfuehrung:
+```Bitte gebe Punkte ein, wobei die Komponenten mit der Leertaste getrennt sind. Dann bestaetige mit Enter. Dabei durfen keine zwei Punkte den selben ersten Wert haben. Mit Shift und Enter kann ein weiterer Punkt hinzugefuegt werden.
+3 5
+4 7
+5 -8
+10 3
+12 0
+
+┌ Info: Eingelesene Punkte
+│   points =
+│    5-element Vector{Tuple{Float32, Float32}}:
+│     (3.0, 5.0)
+│     (4.0, 7.0)
+│     (5.0, -8.0)
+│     (10.0, 3.0)
+└     (12.0, 0.0)
+┌ Info: Berechnete Koeffizienten des Polynoms
+│   coeffs =
+│    5-element Vector{Float32}:
+│     -336.9761904761904
+│      258.4361111111111
+│      -65.99146825396825
+│        6.630555555555556
+└       -0.22757936507936508```
+
+Dabei wird dann auch ein Bild der Grafik erstellt und als svg gespeichert.
+"""
+
+
+# Helping types for safety
+const MaybePoint = Union{Tuple{Float32,Float32},Nothing}
+const PointStack = Vector{Tuple{Float32,Float32}}
+
+"""
+Read and save the inputs from the user.
+When entering nothing the input is finished.
+Otherwise it continues forever.
+
+This does use stdin and stdout.
+"""
+function get_points()::PointStack
+    points::PointStack = Vector()
+    while true
+        point::MaybePoint = read_point()
+        if point == nothing
+            return points
+        end
+        push!(points, point)
+    end
+end
+
+function read_point()::MaybePoint
+    line = strip(readline())
+    parts = split(line)
+    length(parts) == 2 || return nothing
+    vals = try
+        parse.(Float32, parts)
+    catch
+        return nothing
+    end
+    return (vals[1], vals[2])
+end
+
+
+# Simple right shift of any Vector
+shift_right(v::Vector) = [0; v[1:end-1]]
+
+# https://en.wikipedia.org/wiki/Neville%27s_algorithm
+# https://math.stackexchange.com/questions/997348/calculating-coefficients-of-interpolating-polynomial-using-nevilles-algorithm
+function get_coefficients(points, i, j)::Vector
+    i > 0 && j > 0 || error("Cannot evaluate at negative index!")
+    j >= i || error("The second index must be the bigger one!")
+    coeffs = zeros(length(points))
+    if i == j
+        yi = points[i][2]
+        coeffs[1] = yi
+        return coeffs
+    end
+    xi = points[i][1]
+    xj = points[j][1]
+    return (xj * get_coefficients(points, i, j - 1) - shift_right(get_coefficients(points, i, j - 1)) + shift_right(get_coefficients(points, i + 1, j)) - xi * get_coefficients(points, i + 1, j)) / (xj - xi)
+end
+
+get_coefficients(points) = get_coefficients(points, 1, length(points))
+
+function evaluate_coefficients(x, coeffs)::Float32
+    res::Float32 = 0
+    for (i, coeff) in enumerate(coeffs)
+        res += coeff * x^(i - 1)
+    end
+    return res
+end
+
+function plot_points_simple(points, coeffs)
+    OFFSET = 0
+
+    poly(x) = evaluate_coefficients(x, coeffs)
+
+    # Plotten des Polynoms und der Punkte
+    graph_plot = scatter(points, title="Polynom")
+    plot!(poly, minimum(first, points) - OFFSET, maximum(first, points) + OFFSET)
+    bar_plot = bar(coeffs, title="Koeffizienten")
+    plot(graph_plot, bar_plot, legend=false)
+
+    savefig("OutputPlot.svg")
+    gui()
+end
+
+function plot_points_ml(points, exact_coeffs, ml_coeffs, loss_history)
+    exact_poly(x) = evaluate_coefficients(x, exact_coeffs)
+    ml_poly(x) = evaluate_coefficients(x, ml_coeffs)
+
+    # Plotten des Polynoms und der Punkte
+    graph_plot = scatter(points, title="Polynom")
+    plot!(exact_poly, minimum(first, points), maximum(first, points))
+    plot!(ml_poly, minimum(first, points), maximum(first, points))
+
+    loss_plot = plot(loss_history, title="Training Loss")
+    exactbar_plot = bar(exact_coeffs, title="Algo Koeffizienten")
+    mlbar_plot = bar(ml_coeffs, title="Ml Koeffizienten")
+
+    plot(graph_plot, loss_plot, exactbar_plot, mlbar_plot, legend=false)
+    # plot(graph_plot, loss_plot, legend=false)
+
+    savefig("OutputPlotMl.svg")
+    gui()
+end
+
+
+"""
+Main entrypoint to run the program as a interactive script
+"""
+function inter()
+    println("Bitte gebe Punkte ein, wobei die Komponenten mit der Leertaste getrennt sind. Dann bestaetige mit Enter. Dabei durfen keine zwei Punkte den selben ersten Wert haben. Mit Shift und Enter kann ein weiterer Punkt hinzugefuegt werden.")
+
+    points::PointStack = get_points()
+    @info "Eingelesene Punkte" points
+    coeffs = get_coefficients(points)
+    @info "Berechnete Koeffizienten" coeffs
+
+    # Here first, points is short for map(first, points)
+    length(points) > 0 || error("Must enter at least one point!")
+    length(unique(first, points)) == length(points) || error("Points not valid!")
+
+    plot_points_simple(points, coeffs)
+end
+
+
+function generate_training_data()
+    data = []
+    for i in 1:NSAMPLES
+        points = [(rand(), rand()) for _ in 1:NPOINTS]
+        coeffs = get_coefficients(points) # N Vector
+        push!(data, (collect(flatten(points)), coeffs)) # Tuple of 2N input and N solution
+    end
+
+    X = hcat(first.(data)...)
+    Y = hcat(last.(data)...)
+
+    Y_mean = mean(Y, dims=2)
+    Y_std = std(Y, dims=2) .+ eps()
+
+    Y = (Y .- Y_mean) ./ Y_std
+
+    (X, Y, Y_mean, Y_std)
+end
+
+
+p = 2  # power to emphasize larger coefficients
+
+loss(model, x, y) = mean(abs2.(model(x) .- y))
+# loss(model, x, y) = mean(((model(x) .- y) .* (abs.(y) .^ p)).^2)
+# function loss(model, x, y)
+#     y_pred = model(x)
+#     N, B = size(y)                       
+#     powers = reshape(1:N, N, 1)          
+#     errors = abs.(y_pred .- y) .^ powers     
+#     return mean(errors)                  
+# end
+# function loss(model, x, y)
+#     yht = model(x)
+#     N = length(y[:, 1])
+#     weights = collect(map(x -> x^2, 1:N)) ./ N^2
+#     return mean(weights .* abs2.(yht .- y))
+# end
+
+function train_model(Xt, Yt, Xv, Yv)
+    N = size(Yt, 1)
+
+    model = Chain(
+        Dense(2N, 16, relu),  # hidden layer
+        Dense(16, 64, relu),  # hidden layer
+        Dense(64, 32, relu),  # hidden layer
+        Dense(32, 16, relu),  # hidden layer
+        Dense(16, N)         # output layer
+    )
+
+    opti = NAdam(0.001, (0.9, 0.999), 1e-8)
+    opt = Flux.setup(opti, model)
+
+    loss_history = zeros(EPOCHS)
+    for epoch in 1:EPOCHS
+        train!(loss, model, [(Xt, Yt)], opt)  # Pass as a tuple of matrices
+        losss = loss(model, Xv, Yv)
+        loss_history[epoch] = losss
+        if losss < BREAKUP
+            break
+        end
+        # println("=> ", round(epoch/EPOCHS, digits=2))
+        epoch % 100 == 0 && print("\rEpoch $(epoch/EPOCHS), Loss: $(round(losss, digits=6))")
+    end
+    println()
+
+    loss_history = filter(x -> x != 0, loss_history)
+
+    return (model, loss_history)
+end
+
+# TODO: Implement batching of the training data
+const NPOINTS = 4
+const NSAMPLES = 8
+const EPOCHS = 100
+const CHEAT = true
+const SIMPLE = false
+const BREAKUP = 0.01
+
+# TODO: Check functionality
+function f()
+    println("Starting ML. Be patient.")
+
+    X, Y, Y_mean, Y_std = generate_training_data()
+
+    N = size(X, 1)
+    idx = Random.shuffle(1:N)
+    n_train = Int(floor(0.8N))
+    train_idx = idx[1:n_train]
+    val_idx = idx[n_train+1:end]
+
+    Xt = X[:, train_idx]
+    Yt = Y[:, train_idx]
+    Xv = X[:, val_idx]
+    Yv = Y[:, val_idx]
+
+    model, history = train_model(Xt, Yt, Xv, Yv)
+    @info model
+
+    points::PointStack = []
+    index = rand(1:length(X[1, :]))
+    if CHEAT
+        for (i, x) in enumerate(X[:, 1])
+            if i % 2 == 1
+                push!(points, (x, X[:, 1][i+1]))
+            end
+        end
+    else
+        if SIMPLE
+            points = [(0.2, 0.8), (0.5, 0.2), (0.8, 0.8)]
+
+        else
+            points = [(rand(), rand()) for _ in 1:NPOINTS]
+        end
+    end
+
+    xtest = vcat(collect(flatten(points))...)
+    exact_coeffs = get_coefficients(points)
+    ml_coeffs = model(xtest) .* Y_std .+ Y_mean
+
+    plot_points_ml(points, exact_coeffs, ml_coeffs, history)
+end
+
+"""
+Erkenntnisse:
+- Manchmal invertiert das Modell die Koeffizienten
+- Wie kann der Fehler so klein sein, wenn das Modell nicht auswendig lernt und auch nicht gut ist
+- Kleine Fehler in hohen Koeffizienten machen riesige Fehler im Plot
+- Wie kann die Fehlerfunktion besser gemacht werden?
+- Manchmal stimmt die Form aber die Koeffizienten sind um ein verschoben
+"""
+
+# Start the ML part
+# f()
+
+# Start the interactive part
+# inter()