This project provides multiple Java implementations of BLAS, LAPACK, and ARPACK subroutines, supporting Java 8+. It provides hardware acceleration of BLAS, LAPACK, and ARPACK with native implementations like OpenBLAS and Intel MKL.

Usage

Run-time dependencies

• JDK 8+
• [optional] A native library implementing BLAS, LAPACK, or ARPACK installed on the machine
  • ex: OpenBLAS and Intel MKL

Native implementations wrappers

dev.ludovic.netlib relies on native libraries to provide hardware acceleration, and invokes them through JNI with JNIBLAS, JNILAPACK, and JNIARPACK for BLAS, LAPACK, and ARPACK respectively.

These JNIBLAS, JNILAPACK, and JNIARPACK classes distribute and automatically unpack the native JNI wrappers (blas/jni.c, lapack/jni.c, and arpack/jni.c) when needed.

It supports all versions of Java 8+.

Native libraries installation

The native libraries must be installed on the machine; dev.ludovic.netlib doesn't ship any native implementation.

For BLAS and LAPACK, you can install OpenBLAS. For example on Ubuntu:

sudo apt-get install libopenblas-base

For ARPACK, you can install the Fortran77 reference implementation. For example on Ubuntu:

sudo apt-get install libarpack2

To install Intel MKL, follow the instructions at https://software.intel.com/content/www/us/en/develop/tools/oneapi/components/onemkl.html

Overriding the native implementations

The native JNI wrappers dynamically load the native libraries (OpenBLAS or Intel MKL for example). You can override which library is dynamically loaded through two system properties, checked in order:

1. nativeLibPath: the full path to the library
2. nativeLib: the filename of the library; it should be found on the dynamic loader search path (see the search order in man 8 ld.so)

For BLAS, LAPACK, and ARPACK, the system properties are the following:

	nativeLib	nativeLibPath
BLAS	-Ddev.ludovic.netlib.blas.nativeLib set to liblas.so.3 by default	-Ddev.ludovic.netlib.blas.nativeLibPath unset by default
LAPACK	-Ddev.ludovic.netlib.lapack.nativeLib set to liblapack.so.3 by default	-Ddev.ludovic.netlib.lapack.nativeLibPath unset by default
ARPACK	-Ddev.ludovic.netlib.arpack.nativeLib set to libarpack.so.2 by default	-Ddev.ludovic.netlib.arpack.nativeLibPath unset by default

Here are some examples of overriding the loaded native library:

• -Ddev.ludovic.netlib.blas.nativeLibPath=/usr/lib/x86_64-linux-gnu/libopenblas.so for OpenBLAS
• -Ddev.ludovic.netlib.blas.nativeLib=intel_mkl.so for Intel MKL

GPU acceleration

As you can override the native library which is dynamically loaded, you can also load NVBLAS. This native library provides CUDA-based GPU acceleration for some subroutines and automatically falls back to a more generic, CPU-only implementation for other subroutines. You can find the full documentation on how to use it at https://docs.nvidia.com/cuda/nvblas/index.html.

To dynamically load it, you can set either of the above system properties:

• -Ddev.ludovic.netlib.blas.nativeLibPath=/path/to/libnvblas.so
• -Ddev.ludovic.netlib.blas.nativeLib=libnvblas.so

Vector-based acceleration for Java 16+

Java 16 introduced the Vector API, a Java-based implementation providing access to hardware acceleration. VectorBLAS takes advantage of this API to implement most of the BLAS API.

The performance is on-par or above the native libraries on most Level-1 and Level-2 BLAS subroutines. For Level-3 BLAS subroutines, the performance still doesn't match native libraries (some thought on why).

Pure Java fallback for Java 8+

If neither a native implementation nor the Vector API are available, it falls back to a pure Java implementation. For most subroutines, it uses F2j, available in net.sourceforge.f2j:arpack_combined_all:0.1.

For some BLAS subroutines, Java8BLAS and Java11BLAS provide optimized implementations using primitives available in Java 8 and Java 11 respectively.

Build

Dependencies

• JDK 16+ for the Vector API and Foreign Linker API which have been integrated in JDK 16
• net.sourceforge.f2j:arpack_combined_all:0.1 for F2j fallback

Commands

$> mvn clean package

Benchmarks

A set of benchmarks is available in benchmarks/src/main/java/dev/ludovic/netlib/benchmarks/. Run them with:

$> java -jar benchmarks/target/netlib-benchmarks.jar

Release

Update the version in the **/pom.xml, create a tag, and push it:

$> export VERSION=3.0.3
$> git checkout --detach HEAD
$> sed -i -E "s/<version>[0-9]+\-SNAPSHOT<\/version>/<version>$VERSION<\/version>/g" **/pom.xml
$> git commit -p -m "v$VERSION" **/pom.xml
$> git tag v$VERSION
$> git push origin v$VERSION

That will trigger the upload of the package to Sonatype via Github Actions.

Then, go to https://oss.sonatype.org/, go to "Staging Repositories", verify the content of the package, "Close" the package, and finally click "Release" to deploy it to Maven Central.

Finally, go to https://github.com/luhenry/netlib/releases to update and publish the release on the Github repository.

Thanks

This project has been largely inspired by netlib-java and @fommil's hard work.

Contribution

I welcome the addition of any BLAS operation as long as it comes with corresponding tests and benchmarks.