lapack/README.md

node-lapack ===========

node-lapack
===========

A node.js wrapper for the high-performance [LAPACK](http://www.netlib.org/lapack/) linear algebra library.

Prerequisites
=============

This library require LAPACK to be built and installed as a shared library.
In time the entire build process may be unified into this project, but that's
some time away.

In the meantime I've placed some basic LAPACK build instructions at the end of this document.

Installation
============

    npm install lapack

Usage
=====

    var lapack = require('lapack');

    /*
    LAPACK functions
    */

    var result = lapack.sgeqrf([
        [1, 2, 3],
        [3, 4, 5],
        [5, 6, 7]
    ]);

    console.log(result.R);
    console.log(result.tau);

    result = sgesvd('A', 'A', [
        [1, 2, 3],
        [3, 4, 5],
        [5, 6, 7]
    ]);

    console.log(result.U);
    console.log(result.S);
    console.log(result.VT);

    result = lapack.sgetrf([
        [1, 2, 3],
        [3, 4, 5],
        [5, 6, 7]
    ]);

    console.log(result.LU);
    console.log(result.IPIV);

    /*
    conveniently wrapped processes
    */

    // perform a complete LU factorization
    var lu = lapack.lu([
        [1, 2, 3],
        [3, 4, 5],
        [5, 6, 7]
    ]);

    console.log(lu.L);
    console.log(lu.U);
    console.log(lu.P);


    // perform a complete QR factorization
    var qr = lapack.qr([
        [1, 2, 3],
        [3, 4, 5],
        [5, 6, 7]
    ]);

    console.log(qr.Q);
    console.log(qr.R);

    // solve a system of linear equations

    var a = [
    	[2, 4],
    	[2, 8]];

    var b = [[2], 
    	[4]];

    var result = lapack.sgesv(a, b);
    console.log(result.X);
    console.log(result.P);

LAPACK Building
===============

These instructions are raw and a work in progress, but should work fine for linux and MacOS. The net result will be LAPACK and BLAS shared libraries.

If you haven't done so already download the LAPACK source http://www.netlib.org/lapack/

After unpacking the source create a make.inc based on the make.inc.example provided. For the purposes of this document I'll assume you have the "gfortran" fortran compiler installed. 

Then make the following changes:

make.inc
--------

CHANGE:

    FORTRAN  = gfortran
    OPTS     = -O2
    DRVOPTS  = $(OPTS)
    NOOPT    = -O0
    LOADER   = gfortran
    LOADOPTS =

TO:

    UNAME := $(shell uname)

    FORTRAN  = gfortran
    OPTS     = -O2 -fPIC
    DRVOPTS  = $(OPTS)
    NOOPT    = -O0 -fPIC
    LOADER   = gfortran
    LOADOPTS =

    ifeq ($(UNAME), Darwin)
    LIBEXT=dylib
    else
    LIBEXT=so
    endif

BLAS/SRC/Makefile
-----------------

CHANGE:

    all: $(BLASLIB)

TO:

    all: $(BLASLIB) libblas.$(LIBEXT)

    libblas.$(LIBEXT):
        $(FORTRAN) -shared -o $@ *.o
        cp $@ ../../$@

CHANGE:

    clean:
        rm -f *.o

TO:

    clean:
        rm -f *.o
        rm -f *.a
        rm -f *.$(LIBEXT)

SRC/Makefile
------------

CHANGE:

    all: ../$(LAPACKLIB)

TO:

    all: ../$(LAPACKLIB) liblapack.$(LIBEXT)

    liblapack.$(LIBEXT):
        gfortran -shared -o $@ $(ALLOBJ) -lblas -L..
        cp $@ ../$@

CHANGE:

    clean:
        rm -f *.o

TO:

    clean:
        rm -f *.o
        rm -f *.a
        rm -f *.$(LIBEXT)

Compiling
---------

    make blaslib
    make lapacklib

Installing
----------

    # for linux
    cp liblapack.so libblas.so /usr/lib
    # for macos
    # NOTE! this might be dangerous now. macs ship with liblapack.dylib now?
    # regardless, i don't suggest installing a custom lapack right now on Mac
    cp liblapack.dylib libblas.dylib /usr/lib


License
=======

Copyright (c) 2011, Chris Umbel

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.