feat: initial release

Assisted-by: GLM 5.3 Flash

stats/degenerate_input_pin_test.go

@@ -0,0 +1,74 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package stats
+
+import (
+	"sourcedock.dev/petrbalvin/tensor/internal/core"
+	"testing"
+)
+
+// TestPoissonDrawsZeroLambda pins the degenerate distribution: λ = 0
+// must draw 0, never the −1 the multiplication loop used to hand back.
+func TestPoissonDrawsZeroLambda(t *testing.T) {
+	g := core.NewGenerator(7)
+	out, err := PoissonDraws(g, 16, 0)
+	if err != nil {
+		t.Fatalf("PoissonDraws: %v", err)
+	}
+	for i := range 16 {
+		if out.FloatAt(i) != 0 {
+			t.Fatalf("draw %d = %g, want 0", i, out.FloatAt(i))
+		}
+	}
+}
+
+// TestChiSquareComplexRejects pins the dtype guard.
+func TestChiSquareComplexRejects(t *testing.T) {
+	obs, err := core.FromComplexes([]complex128{1, 2, 3}, 3)
+	if err != nil {
+		t.Fatalf("FromComplexes: %v", err)
+	}
+	exp, _ := core.FromFloats([]float64{1, 2, 3}, 3)
+	if _, _, _, err := ChiSquareGoodnessOfFit(obs, exp); err == nil {
+		t.Fatal("ChiSquareGoodnessOfFit accepted complex observed")
+	}
+	if _, _, _, err := ChiSquareGoodnessOfFit(exp, obs); err == nil {
+		t.Fatal("ChiSquareGoodnessOfFit accepted complex expected")
+	}
+}
+
+// TestBootstrapCIFreshArray pins the documented contract: a statistic
+// that retains its argument must observe values frozen at call time,
+// never the next resample's mutation through the shared buffer.
+func TestBootstrapCIFreshArray(t *testing.T) {
+	data, err := core.FromFloats([]float64{1, 2, 3, 4, 5, 6, 7, 8}, 8)
+	if err != nil {
+		t.Fatalf("FromFloats: %v", err)
+	}
+	type snapshot struct {
+		arr  *core.Array
+		mean float64
+	}
+	var kept []snapshot
+	stat := func(a *core.Array) (float64, error) {
+		m, err := core.Mean(a)
+		if err != nil {
+			return 0, err
+		}
+		kept = append(kept, snapshot{a, m})
+		return m, nil
+	}
+	if _, _, err := BootstrapCI(data, stat, 0.9, 8, 42); err != nil {
+		t.Fatalf("BootstrapCI: %v", err)
+	}
+	for i, s := range kept {
+		m, err := core.Mean(s.arr)
+		if err != nil {
+			t.Fatalf("kept[%d] mean: %v", i, err)
+		}
+		if m != s.mean {
+			t.Fatalf("kept[%d] mean drifted from %g to %g (buffer was mutated)", i, s.mean, m)
+		}
+	}
+}