la-stack 0.4.3

Fast, stack-allocated linear algebra for fixed dimensions
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

# Benchmark Performance

**la-stack** v0.4.3 · `45affa8` (HEAD) · 2026-06-09 08:41:32 UTC
**Statistic**: median
**Suite**: all
**Scope**: release-signal

## Benchmark Results

Comparison against baseline **v0.4.2**:

Negative change = faster. Speedup > 1.00x = improvement.

## Exact arithmetic

### D=2

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det | 0.9 ns | 0.7 ns | **-24.0%** | 1.32x |
| det_direct | 1.0 ns | 1.0 ns | +2.1% | 0.98x |
| det_exact | 248.9 ns | 195.6 ns | **-21.4%** | 1.27x |
| det_exact_f64_result (vs det_exact_f64) | 429.1 ns | 167.6 ns | **-60.9%** | 2.56x |
| det_exact_rounded_f64 (vs det_exact_f64) | 429.1 ns | 375.2 ns | **-12.6%** | 1.14x |
| det_sign_exact | 1.5 ns | 3.2 ns | +115.9% | 0.46x |
| solve_exact | 6.53 µs | 6.45 µs | **-1.1%** | 1.01x |
| solve_exact_f64_result (vs solve_exact_f64) | 6.90 µs | 6.60 µs | **-4.4%** | 1.05x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 6.90 µs | 7.02 µs | +1.7% | 0.98x |

### D=3

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det | 1.8 ns | 1.5 ns | **-19.4%** | 1.24x |
| det_direct | 2.0 ns | 2.0 ns | +2.4% | 0.98x |
| det_exact | 739.0 ns | 468.6 ns | **-36.6%** | 1.58x |
| det_exact_f64_result (vs det_exact_f64) | 913.1 ns | 435.6 ns | **-52.3%** | 2.10x |
| det_exact_rounded_f64 (vs det_exact_f64) | 913.1 ns | 648.1 ns | **-29.0%** | 1.41x |
| det_sign_exact | 4.2 ns | 5.5 ns | +30.9% | 0.76x |
| solve_exact | 25.69 µs | 25.16 µs | **-2.1%** | 1.02x |
| solve_exact_f64_result (vs solve_exact_f64) | 26.16 µs | 25.42 µs | **-2.8%** | 1.03x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 26.16 µs | 25.67 µs | **-1.9%** | 1.02x |

### D=4

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det | 3.3 ns | 4.5 ns | +38.1% | 0.72x |
| det_direct | 3.7 ns | 4.3 ns | +17.6% | 0.85x |
| det_exact | 1.87 µs | 1.47 µs | **-21.8%** | 1.28x |
| det_exact_f64_result (vs det_exact_f64) | 2.04 µs | 1.47 µs | **-27.9%** | 1.39x |
| det_exact_rounded_f64 (vs det_exact_f64) | 2.04 µs | 1.63 µs | **-19.8%** | 1.25x |
| det_sign_exact | 6.9 ns | 11.5 ns | +67.1% | 0.60x |
| solve_exact | 64.95 µs | 61.67 µs | **-5.1%** | 1.05x |
| solve_exact_f64_result (vs solve_exact_f64) | 66.35 µs | 62.37 µs | **-6.0%** | 1.06x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 66.35 µs | 63.59 µs | **-4.2%** | 1.04x |

### D=5

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det | 26.0 ns | 23.3 ns | **-10.6%** | 1.12x |
| det_direct | 4.5 ns | 2.5 ns | **-44.2%** | 1.79x |
| det_exact | 4.10 µs | 4.05 µs | **-1.3%** | 1.01x |
| det_exact_f64_result (vs det_exact_f64) | 4.21 µs | 4.02 µs | **-4.4%** | 1.05x |
| det_exact_rounded_f64 (vs det_exact_f64) | 4.21 µs | 4.33 µs | +2.8% | 0.97x |
| det_sign_exact | 3.94 µs | 3.96 µs | +0.6% | 0.99x |
| solve_exact | 130.82 µs | 126.75 µs | **-3.1%** | 1.03x |
| solve_exact_f64_result (vs solve_exact_f64) | 132.70 µs | 127.37 µs | **-4.0%** | 1.04x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 132.70 µs | 128.15 µs | **-3.4%** | 1.04x |

### Near-singular 3x3

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det_sign_exact | 705.2 ns | 444.2 ns | **-37.0%** | 1.59x |
| det_exact | 724.0 ns | 478.9 ns | **-33.9%** | 1.51x |
| solve_exact | 3.44 µs | 3.39 µs | **-1.6%** | 1.02x |
| solve_exact_f64_result (vs solve_exact_f64) | 3.47 µs | 3.36 µs | **-3.2%** | 1.03x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 3.47 µs | 3.39 µs | **-2.5%** | 1.03x |

### Large entries 3x3

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det_sign_exact | 2.91 µs | 402.4 ns | **-86.2%** | 7.23x |
| det_exact | 2.94 µs | 434.0 ns | **-85.2%** | 6.76x |
| solve_exact | 82.81 µs | 81.57 µs | **-1.5%** | 1.02x |
| solve_exact_f64_result (vs solve_exact_f64) | 84.32 µs | 81.66 µs | **-3.1%** | 1.03x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 84.32 µs | 82.04 µs | **-2.7%** | 1.03x |

### Hilbert 4x4

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det_sign_exact | 6.9 ns | 11.5 ns | +66.4% | 0.60x |
| det_exact | 1.91 µs | 1.50 µs | **-21.7%** | 1.28x |
| solve_exact | 49.42 µs | 47.77 µs | **-3.3%** | 1.03x |
| solve_exact_f64_result (vs solve_exact_f64) | 50.38 µs | 47.67 µs | **-5.4%** | 1.06x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 50.38 µs | 48.17 µs | **-4.4%** | 1.05x |

### Hilbert 5x5

| Benchmark | v0.4.2 | Latest | Change | Speedup |
|-----------|-------:|-------:|-------:|--------:|
| det_sign_exact | 4.09 µs | 3.91 µs | **-4.6%** | 1.05x |
| det_exact | 4.00 µs | 4.02 µs | +0.6% | 0.99x |
| solve_exact | 98.71 µs | 95.41 µs | **-3.4%** | 1.03x |
| solve_exact_f64_result (vs solve_exact_f64) | 99.88 µs | 98.14 µs | **-1.7%** | 1.02x |
| solve_exact_rounded_f64 (vs solve_exact_f64) | 99.88 µs | 97.50 µs | **-2.4%** | 1.02x |

## How to Update

Local performance reports are generated in isolated temporary worktrees:

```bash
# Local development: compare the current tree with the latest release
just performance-local

# Release PR: update docs/PERFORMANCE.md and archive the previous report
just performance-release

# GitHub Actions release assets
just performance-github-assets

# Explicit repair
just performance-release <current-tag> <previous-tag>
```

`just performance-local` writes `target/bench-reports/performance.md`.
`just performance-github-assets` writes `target/bench-reports/github-assets-performance.md`.

Older curated release-to-release reports are archived in `docs/archive/performance/`.

See `docs/BENCHMARKING.md` for the full comparison workflow.