NAME

       Math::GSL::Interp - Interpolation

SYNOPSIS

           use Math::GSL::Interp qw/:all/;
           my $x_array = [ 0.0, 1.0, 2.0, 3.0, 4.0 ];

           # check that we get the last interval if x == last value
           $index_result = gsl_interp_bsearch($x_array, 4.0, 0, 4);
           print "The last interval is $index_result \n";

DESCRIPTION

       "gsl_interp_accel_alloc()"
        This function returns a pointer to an accelerator object, which is a kind of iterator for interpolation
        lookups. It tracks the state of lookups, thus allowing for application of various acceleration
        strategies.

       "gsl_interp_accel_find($a, $x_array, $size, $x)"
        This function performs a lookup action on the data array $x_array of size $size, using the given
        accelerator $a. This is how lookups are performed during evaluation of an interpolation. The function
        returns an index i such that $x_array[i] <= $x < $x_array[i+1].

       "gsl_interp_accel_reset"
       "gsl_interp_accel_free($a)"
        This function frees the accelerator object $a.

       "gsl_interp_alloc($T, $alloc)"
        This function returns a newly allocated interpolation object of type $T for $size data-points. $T must
        be one of the constants below.

       "gsl_interp_init($interp, $xa, $ya, $size)"
        This function initializes the interpolation object interp for the data (xa,ya) where xa and ya are
        arrays of size size. The interpolation object (gsl_interp) does not save the data arrays xa and ya and
        only stores the static state computed from the data. The xa data array is always assumed to be strictly
        ordered, with increasing x values; the behavior for other arrangements is not defined.

       "gsl_interp_name($interp)"
        This function returns the name of the interpolation type used by $interp.

       "gsl_interp_min_size($interp)"
        This function returns the minimum number of points required by the interpolation type of $interp. For
        example, Akima spline interpolation requires a minimum of 5 points.

       "gsl_interp_eval_e($interp, $xa, $ya, $x, $acc)"
        This functions returns the interpolated value of y for a given point $x, using the interpolation object
        $interp, data arrays $xa and $ya and the accelerator $acc. The function returns 0 if the operation
        succeeded, 1 otherwise and the y value.

       "gsl_interp_eval($interp, $xa, $ya, $x, $acc)"
        This functions returns the interpolated value of y for a given point $x, using the interpolation object
        $interp, data arrays $xa and $ya and the accelerator $acc.

       "gsl_interp_eval_deriv_e($interp, $xa, $ya, $x, $acc)"
        This function computes the derivative value of y for a given point $x, using the interpolation object
        $interp, data arrays $xa and $ya and the accelerator $acc. The function returns 0 if the operation
        succeeded, 1 otherwise and the d value.

       "gsl_interp_eval_deriv($interp, $xa, $ya, $x, $acc)"
        This function returns the derivative d of an interpolated function for a given point $x, using the
        interpolation object interp, data arrays $xa and $ya and the accelerator $acc.

       "gsl_interp_eval_deriv2_e($interp, $xa, $ya, $x, $acc)"
        This function computes the second derivative d2 of an interpolated function for a given point $x, using
        the interpolation object $interp, data arrays $xa and $ya and the accelerator $acc. The function returns
        0 if the operation succeeded, 1 otherwise and the d2 value.

       "gsl_interp_eval_deriv2($interp, $xa, $ya, $x, $acc)"
        This function returns the second derivative d2 of an interpolated function for a given point $x, using
        the interpolation object $interp, data arrays $xa and $ya and the accelerator $acc.

       "gsl_interp_eval_integ_e($interp, $xa, $ya, $a, $b, $acc)"
        This function computes the numerical integral result of an interpolated function over the range [$a,
        $b], using the interpolation object $interp, data arrays $xa and $ya and the accelerator $acc. The
        function returns 0 if the operation succeeded, 1 otherwise and the result value.

       "gsl_interp_eval_integ($interp, $xa, $ya, $a, $b, $acc)"
        This function returns the numerical integral result of an interpolated function over the range [$a, $b],
        using the interpolation object $interp, data arrays $xa and $ya and the accelerator $acc.

       "gsl_interp_free($interp)" - This function frees the interpolation object $interp.
       "gsl_interp_bsearch($x_array, $x, $index_lo, $index_hi)"
        This function returns the index i of the array $x_array such that $x_array[i] <= x < $x_array[i+1]. The
        index is searched for in the range [$index_lo,$index_hi].

       This module also includes the following constants :

       $gsl_interp_linear
        Linear interpolation

       $gsl_interp_polynomial
        Polynomial interpolation. This method should only be used for interpolating small numbers of points
        because polynomial interpolation introduces large oscillations, even for well-behaved datasets. The
        number of terms in the interpolating polynomial is equal to the number of points.

       $gsl_interp_cspline
        Cubic spline with natural boundary conditions. The resulting curve is piecewise cubic on each interval,
        with matching first and second derivatives at the supplied data-points. The second derivative is chosen
        to be zero at the first point and last point.

       $gsl_interp_cspline_periodic
        Cubic spline with periodic boundary conditions. The resulting curve is piecewise cubic on each interval,
        with matching first and second derivatives at the supplied data-points. The derivatives at the first and
        last points are also matched. Note that the last point in the data must have the same y-value as the
        first point, otherwise the resulting periodic interpolation will have a discontinuity at the boundary.

       $gsl_interp_akima
        Non-rounded Akima spline with natural boundary conditions. This method uses the non-rounded corner
        algorithm of Wodicka.

       $gsl_interp_akima_periodic
        Non-rounded Akima spline with periodic boundary conditions. This method uses the non-rounded corner
        algorithm of Wodicka.

AUTHORS

       Jonathan "Duke" Leto <jonathan@leto.net> and Thierry Moisan <thierry.moisan@gmail.com>

COPYRIGHT AND LICENSE

       Copyright (C) 2008-2011 Jonathan "Duke" Leto and Thierry Moisan

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself.