feat: initial release

Assisted-by: GLM 5.3 Flash

optim/callback_pins_test.go

@@ -0,0 +1,73 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package optim
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"sourcedock.dev/petrbalvin/tensor/internal/core"
+)
+
+// Callback-contract pins: a gradient callback that returns a shorter
+// array than the problem has dimensions used to index past it, and a
+// differential-evolution population below four has no way to draw
+// three distinct others.
+
+// TestLBFGSGradientLength pins the callback contract.
+func TestLBFGSGradientLength(t *testing.T) {
+	f := func(p *core.Array) (float64, error) {
+		x, y := p.FloatAt(0), p.FloatAt(1)
+		return x*x + y*y, nil
+	}
+	short, err := core.FromFloats([]float64{1}, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	grad := func(*core.Array) (*core.Array, error) { return short, nil }
+	start, err := core.FromFloats([]float64{1, 1}, 2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, _, err := MinimiseLBFGS(f, grad, start, LBFGSOptions{}); err == nil {
+		t.Fatal("expected an error for a gradient of the wrong length")
+	} else if !strings.Contains(err.Error(), "gradient callback") {
+		t.Fatalf("error = %v, want a callback-length refusal", err)
+	}
+}
+
+// TestDifferentialEvolutionPopulationFloor pins the option contract: a
+// population below four has no way to draw three distinct others, and
+// the search used to spin in the picking loop for ever.
+func TestDifferentialEvolutionPopulationFloor(t *testing.T) {
+	lo, err := core.FromFloats([]float64{-5}, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	hi, err := core.FromFloats([]float64{5}, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f := func(p *core.Array) (float64, error) { v := p.FloatAt(0); return v * v, nil }
+	done := make(chan error, 1)
+	go func() {
+		_, _, err := MinimiseDifferentialEvolution(f, lo, hi, DifferentialEvolutionOptions{Population: 3, Generations: 5})
+		done <- err
+	}()
+	select {
+	case err := <-done:
+		if err == nil {
+			t.Fatal("expected an error for a population of 3")
+		} else if !strings.Contains(err.Error(), "population") {
+			t.Fatalf("error = %v, want a population refusal", err)
+		}
+	case <-time.After(10 * time.Second):
+		t.Fatal("MinimiseDifferentialEvolution did not return: the picking loop spins")
+	}
+	// The floor itself still works.
+	if _, _, err := MinimiseDifferentialEvolution(f, lo, hi, DifferentialEvolutionOptions{Population: 4, Generations: 20}); err != nil {
+		t.Fatalf("population 4: %v", err)
+	}
+}