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2. Using the GSL Modules

To use one of the GSL modules in a S-lang script, the module must first be loaded using the require function. For example, to load the GSL special function module, use

   require ("gslsf");

The gsl.sl file exists as a convenient way to load all GSL modules (gslsf, gslrand, etc.), e.g.,

    require ("gsl");

Finally, it may be desirable to import the GSL module into a separate namespace. For example, to load the GSL special function module gslsf into a namespace called GSL, use

   require ("gsl", "G")
Then to access, e.g., the hypot function, use the GSL->hypot. See the S-Lang documentation for more information about namespaces.

Once the desired module has been loaded, intrinsics functions and variables defined by the module may be used in the usual way, e.g.,

    require ("gslsf");
        .
        .
    % Use the GSL hypot function to filter a list of (x,y) pairs
    % to those values that fall in a circle of radius R centered 
    % on (0,0)
    define filter_region_in_circle (x, y, R)
    {
       variable i = where (hypot (x,y) < R);
       return (x[i], y[i]);
    }


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