trnblas 0.4.2

BLAS operations for AWS Trainium via NKI

trnblas

BLAS operations for AWS Trainium via NKI (Neuron Kernel Interface).

Trainium ships no BLAS library. trnblas provides Level 1-3 BLAS operations with NKI kernel acceleration on the Tensor Engine, targeting scientific computing workloads that are GEMM-dominated.

Part of the trnsci scientific computing suite (github.com/trnsci).

Why

NVIDIA has cuBLAS with 152 optimized routines. Trainium has torch.matmul. That's fine for ML training but insufficient for scientific computing codes that need TRSM, SYRK, SYMM, and batched GEMM with specific transpose/scaling semantics.

trnblas closes this gap — same BLAS API surface, NKI-accelerated GEMM on Trainium, PyTorch fallback everywhere else.

Install

pip install trnblas

# With Neuron hardware support
pip install trnblas[neuron]

Usage

import torch
import trnblas

# Level 3 — Matrix multiply (the hot path)
C = trnblas.gemm(alpha=1.0, A=A, B=B, beta=0.5, C=C_init, transA=True)

# Batched GEMM (DF-MP2 tensor contractions)
C = trnblas.batched_gemm(1.0, A_batch, B_batch)

# Symmetric matrix multiply (Fock builds)
F = trnblas.symm(1.0, density, H_core, side="left")

# Triangular solve (Cholesky-based density fitting)
X = trnblas.trsm(1.0, L, B, uplo="lower")

# Symmetric rank-k update (metric construction)
J = trnblas.syrk(1.0, integrals, trans=True)

# Level 2 — Matrix-vector
y = trnblas.gemv(1.0, A, x, beta=1.0, y=y)

# Level 1 — Vector operations
y = trnblas.axpy(alpha, x, y)
d = trnblas.dot(x, y)
n = trnblas.nrm2(x)

DF-MP2 Example

# Run the density-fitted MP2 example
python examples/df_mp2.py --demo
python examples/df_mp2.py --nbasis 100 --nocc 20

The example demonstrates all core BLAS operations in a realistic quantum chemistry workflow: Cholesky factorization, triangular solve, half-transform GEMMs, metric contraction, and energy evaluation.

Real-molecule validation (via PySCF)

pip install trnblas[pyscf]
python examples/df_mp2_pyscf.py                       # H2O / STO-3G
python examples/df_mp2_pyscf.py --mol ch4 --basis cc-pvdz

Runs SCF + density fitting via PySCF, feeds the integrals through trnblas, and compares to PySCF's own DF-MP2 reference energy. Matches to < 10⁻⁷ Hartree on H2O, CH4, NH3 at cc-pvdz.

Operations

Level	Operation	Description
1	axpy	y = αx + y
1	dot	x^T y
1	nrm2	‖x‖₂
1	scal	x = αx
1	asum	Σ|xᵢ|
1	iamax	argmax |xᵢ|
2	gemv	y = α op(A) x + βy
2	symv	y = α A x + βy (A symmetric)
2	trmv	x = op(A) x (A triangular)
2	ger	A = α x yᵀ + A
3	gemm	C = α op(A) op(B) + βC
3	batched_gemm	Batched GEMM
3	symm	C = α A B + βC (A symmetric)
3	syrk	C = α A Aᵀ + βC
3	trsm	Solve op(A) X = αB
3	trmm	B = α op(A) B

Status

• Level 1-3 BLAS with PyTorch backend
• GEMM with NKI dispatch stub
• DF-MP2 example
• NKI GEMM kernel validation on trn1/trn2
• NKI GEMM with stationary tile reuse
• Batched GEMM NKI kernel
• Double-double FP64 emulation
• Benchmarks vs cuBLAS

Related Projects

Project	What
trnfft	FFT + complex ops for Trainium
trnrand	Random number generation (Philox/Sobol) for Trainium
trnsolver	Linear solvers and eigendecomposition

License

Apache 2.0 — Copyright 2026 Scott Friedman