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Interface Dart with the GNU Scientific Library gsl .

Features

GSL covers a large number of mathematical topics. See the extremely well written manual for details. These bindings are done for GLS version2.7.1.

Getting started

import 'package:gsl_dart/gsl_dart.dart';

main() {
  /// Calculate the value of Bessel's J0 function at 5:  
  print(gsl.gsl_sf_bessel_J0(5.0)); // -0.17759677131433826  
}

Usage

Nonlinear optimization

TODO: Include short and useful examples for package users. Add longer examples to /example folder.

const like = 'sample';

Additional information

How to install gsl on Ubuntu 22.04

Download the gsl-2.7.1.tar.gz file.

Gunzip it: gunzip gsl-2.7.1.tar.gz

Untar it: tar -xvf gsl-2.7.1.tar

Reading the INSTALL file says that doing ./configure && make && make install should configure, build and install the package. It does, but it won't be enough to allow for a full Dart interop. Why? If you proceed as mentioned above, the dynamic library libgsl.so gets created in /usr/local/lib but it doesn't link to the BLAS library libgslcblas.so. You can check

ldd /usr/local/lib/libgsl.so
        linux-vdso.so.1 (0x00007ffe1f174000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fcf9577d000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fcf95000000)

To enable all the linear algebra functionality that comes with BLAS, you need to install it and then link it correctly. To install BLAS do

sudo apt-get install libblas-dev liblapack-dev

It will install the dynamic library in /usr/local/lib/libgslcblas.so.

You need to customize the existing configure file, because otherwise the resulting libgsl.so does not link to libgslcblas.so. To do this, edit the configure.ac file as specified in https://www.gnu.org/software/gsl/doc/html/autoconf.html.

at line 131 or so, add

AC_CHECK_LIB([m],[cos])

# ------------------------------------------------------------------
# Check for BLAS
# ------------------------------------------------------------------
AC_CHECK_LIB([cblas],[cblas_dgemm],[],[
  echo "Library libcblas not found. Looking for GSL cblas." 
  echo -n " The present value of LDFLAGS is: " 
  echo $LDFLAGS
  AC_CHECK_LIB([gslcblas],[cblas_dgemm],[],[
    echo "Library libgslcblas not found. gsl_dart requires a cblas library." 
    echo "You may be required to add a cblas library to the LIBS "
    echo "environment variable. "
    echo ""
    echo -n " The present value of LDFLAGS is: " 
    echo $LDFLAGS
    echo ""
  ],[])
],[])

# ------------------------------------------------------------------
# Check for GSL library (must check for BLAS first)
# ------------------------------------------------------------------
AC_CHECK_LIB([gsl], [gsl_vector_get], [], 
	[echo ""
        echo "GSL not found."
        echo "gsl_dart requires the GSL library."
	echo ""
	echo -n " The present value of LDFLAGS is: " 
	echo $LDFLAGS
        exit -1
	],[])

Run autoreconf --verbose --install --force to create the Makefile.

Now install it: ./configure && make && make install.

To check that you libgslcblas.so is linked properly, check that it exists in the list of dependencies:

ldd /usr/local/lib/libgsl.so
        linux-vdso.so.1 (0x00007ffe1f174000)
        libgslcblas.so.0 => /usr/local/lib/libgslcblas.so.0 (0x00007fcf95879000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fcf9577d000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fcf95000000)

Make gsl available in Dart

As a user, you don't need this step. It's only needed as a package author.

According to the ffigen documentation, you need to have LLVM (9+) installed. You can install it with sudo apt-get install libclang-dev. It gets installed in the usr/lib/llvm-14 folder.

Go through the source folders of gsl-2.7.1 to extract all the header files needed for the ffigen package to generate the Dart bindings. For example, get the gsl-2.7.1/blas/gsl_blas.h, gsl-2.7.1/blas/gsl_blas_types.h files from the blas folder, etc. Put all these header files in the ./third_party folder. Boring but needed.

Check out the pubspec.yaml section for the ffigen. Note how it refers to the ./third_party folder.

Run dart run ffigen to generate the bindings. They get generated in ./src/gsl_generated_bindings.dart as specified in the pubspec.yaml file.

There are a bunch of [SEVERE] warnings due to the gsl_spmatrix_pool not being found. That means the sparse matrix functionality is not working properly. TODO: fix it. There are also multiple other errors with functions not found, etc.

Run a C example

See for example the example/eigen.c file. Run gcc -Wall -o eigen eigen.c -lgsl -lgslcblas -lm. Then ./eigen and you will see output.

To see the dynamic dependencies do ldd eigen to get

$ ldd eigen
    linux-vdso.so.1 (0x00007ffe83ffa000)
    libgsl.so.27 => /usr/local/lib/libgsl.so.27 (0x00007f9b5b400000)
    libgslcblas.so.0 => /usr/local/lib/libgslcblas.so.0 (0x00007f9b5b6eb000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9b5b000000)
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f9b5b319000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f9b5b749000)

You can find the names of the symbols with nm /usr/local/lib/libgslcblas.so.