39 lines
1.1 KiB
Go
39 lines
1.1 KiB
Go
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: MIT
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package grad
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import "testing"
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// TestHessianVectorProductZeroDirectionShape pins the repair: a zero
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// direction returned a flat length-n vector while
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// every other answer carries the point's own shape.
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func TestHessianVectorProductZeroDirectionShape(t *testing.T) {
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x0 := []float64{0.5, -1.25, 2, -2}
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xt, err := FromFloat64s(x0, false, 2, 2)
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if err != nil {
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t.Fatalf("FromFloat64s: %v", err)
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}
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f := func(z *Tensor) (*Tensor, error) { return z.Sum() }
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v, err := FromFloat64s(make([]float64, 4), false, 2, 2)
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if err != nil {
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t.Fatalf("FromFloat64s: %v", err)
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}
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hv, err := HessianVectorProduct(f, xt, v, HessianOptions{})
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if err != nil {
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t.Fatalf("HessianVectorProduct: %v", err)
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}
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want := []int{2, 2}
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got := hv.Shape()
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for i := range want {
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if got[i] != want[i] {
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t.Fatalf("H·0 shape = %v, want %v", got, want)
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}
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}
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for i := range 4 {
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if hv.FloatAt(i) != 0 {
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t.Fatalf("H·0 = %v, want the zero matrix", hv.FloatAt(i))
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}
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}
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}
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