NAME

       PDL::GSL::INTERP - PDL interface to Interpolation routines in GSL

DESCRIPTION

       This is an interface to the interpolation package present in the GNU Scientific Library.

SYNOPSIS

          use PDL;
          use PDL::GSL::INTERP;

          my $x = sequence(10);
          my $y = exp($x);

          my $spl = PDL::GSL::INTERP->init('cspline',$x,$y);

          my $res = $spl->eval(4.35);
          $res = $spl->deriv(4.35);
          $res = $spl->deriv2(4.35);
          $res = $spl->integ(2.1,7.4);

NOMENCLATURE

       Throughout this documentation we strive to use the same variables that are present in the original GSL
       documentation (see See Also). Oftentimes those variables are called "a" and "b". Since good Perl coding
       practices discourage the use of Perl variables $a and $b, here we refer to Parameters "a" and "b" as $pa
       and $pb, respectively, and Limits (of domain or integration) as $la and $lb.

FUNCTIONS

   init()
       The init method initializes a new instance of INTERP. It needs as input an interpolation type and two
       piddles holding the x and y values to be interpolated. The GSL routines require that x be monotonically
       increasing and a quicksort is performed by default to ensure that. You can skip the quicksort by passing
       the option {Sort => 0}.

       The available interpolation types are :

       linear
       polynomial
       cspline (natural cubic spline)
       cspline_periodic  (periodic cubic spline)
       akima (natural akima spline)
       akima_periodic  (periodic akima spline)

       Please check the GSL documentation for more information.

       Usage:

           $blessed_ref = PDL::GSL::INTERP->init($interp_method,$x,$y,$opt);

       Example:

           $x = sequence(10);
           $y = exp($x);

           $spl = PDL::GSL::INTERP->init('cspline',$x,$y)
           $spl = PDL::GSL::INTERP->init('cspline',$x,$y,{Sort => 1}) #same as above

           # no sorting done on x, user is certain that x is monotonically increasing
           $spl = PDL::GSL::INTERP->init('cspline',$x,$y,{Sort => 0});

   eval()
       The function eval returns the interpolating function at a given point. By default it will barf if you try
       to  extrapolate,  to  comply  silently  if  the  point  to  be  evaluated is out of range pass the option
       {Extrapolate => 1}

       Usage:

           $result = $spl->eval($points,$opt);

       Example:

           my $res = $spl->eval($x)
           $res = $spl->eval($x,{Extrapolate => 0}) #same as above

           # silently comply if $x is out of range
           $res = $spl->eval($x,{Extrapolate => 1})

   deriv()
       The deriv function returns the derivative of the interpolating function at a given point. By  default  it
       will barf if you try to extrapolate, to comply silently if the point to be evaluated is out of range pass
       the option {Extrapolate => 1}

       Usage:

           $result = $spl->deriv($points,$opt);

       Example:

           my $res = $spl->deriv($x)
           $res = $spl->deriv($x,{Extrapolate => 0}) #same as above

           # silently comply if $x is out of range
           $res = $spl->deriv($x,{Extrapolate => 1})

   deriv2()
       The  deriv2  function  returns  the  second derivative of the interpolating function at a given point. By
       default it will barf if you try to extrapolate, to comply silently if the point to be evaluated is out of
       range pass the option {Extrapolate => 1}

       Usage:

           $result = $spl->deriv2($points,$opt);

       Example:

           my $res = $spl->deriv2($x)
           $res = $spl->deriv2($x,{Extrapolate => 0}) #same as above

           # silently comply if $x is out of range
           $res = $spl->deriv2($x,{Extrapolate => 1})

   integ()
       The integ function returns the integral of the interpolating function between two points.  By default  it
       will  barf if you try to extrapolate, to comply silently if one of the integration limits is out of range
       pass the option {Extrapolate => 1}

       Usage:

           $result = $spl->integ($la,$lb,$opt);

       Example:

           my $res = $spl->integ($la,$lb)
           $res = $spl->integ($x,$y,{Extrapolate => 0}) #same as above

           # silently comply if $la or $lb are out of range
           $res = $spl->eval($la,$lb,{Extrapolate => 1})

BUGS

       Feedback is welcome.

SEE ALSO

       PDL

       The        GSL        documentation        for         interpolation         is         online         at
       <https://www.gnu.org/software/gsl/doc/html/interp.html>

AUTHOR

       This file copyright (C) 2003 Andres Jordan <andresj@physics.rutgers.edu> All rights reserved. There is no
       warranty.  You  are  allowed  to  redistribute  this software/documentation under certain conditions. For
       details, see the file COPYING  in  the  PDL  distribution.  If  this  file  is  separated  from  the  PDL
       distribution, the copyright notice should be included in the file.

       The GSL interpolation module was written by Gerard Jungman.

perl v5.30.0                                       2020-01-18                                        INTERP(3pm)