74 lines
2.4 KiB
Go
74 lines
2.4 KiB
Go
// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: MIT
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package optim
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import (
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"strings"
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"testing"
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"time"
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"sourcedock.dev/petrbalvin/tensor/internal/core"
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)
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// Callback-contract pins: a gradient callback that returns a shorter
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// array than the problem has dimensions used to index past it, and a
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// differential-evolution population below four has no way to draw
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// three distinct others.
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// TestLBFGSGradientLength pins the callback contract.
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func TestLBFGSGradientLength(t *testing.T) {
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f := func(p *core.Array) (float64, error) {
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x, y := p.FloatAt(0), p.FloatAt(1)
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return x*x + y*y, nil
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}
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short, err := core.FromFloats([]float64{1}, 1)
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if err != nil {
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t.Fatal(err)
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}
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grad := func(*core.Array) (*core.Array, error) { return short, nil }
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start, err := core.FromFloats([]float64{1, 1}, 2)
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if err != nil {
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t.Fatal(err)
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}
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if _, _, err := MinimiseLBFGS(f, grad, start, LBFGSOptions{}); err == nil {
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t.Fatal("expected an error for a gradient of the wrong length")
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} else if !strings.Contains(err.Error(), "gradient callback") {
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t.Fatalf("error = %v, want a callback-length refusal", err)
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}
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}
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// TestDifferentialEvolutionPopulationFloor pins the option contract: a
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// population below four has no way to draw three distinct others, and
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// the search used to spin in the picking loop for ever.
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func TestDifferentialEvolutionPopulationFloor(t *testing.T) {
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lo, err := core.FromFloats([]float64{-5}, 1)
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if err != nil {
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t.Fatal(err)
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}
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hi, err := core.FromFloats([]float64{5}, 1)
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if err != nil {
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t.Fatal(err)
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}
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f := func(p *core.Array) (float64, error) { v := p.FloatAt(0); return v * v, nil }
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done := make(chan error, 1)
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go func() {
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_, _, err := MinimiseDifferentialEvolution(f, lo, hi, DifferentialEvolutionOptions{Population: 3, Generations: 5})
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done <- err
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}()
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select {
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case err := <-done:
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if err == nil {
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t.Fatal("expected an error for a population of 3")
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} else if !strings.Contains(err.Error(), "population") {
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t.Fatalf("error = %v, want a population refusal", err)
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}
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case <-time.After(10 * time.Second):
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t.Fatal("MinimiseDifferentialEvolution did not return: the picking loop spins")
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}
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// The floor itself still works.
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if _, _, err := MinimiseDifferentialEvolution(f, lo, hi, DifferentialEvolutionOptions{Population: 4, Generations: 20}); err != nil {
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t.Fatalf("population 4: %v", err)
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}
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}
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