INTERP(3) User Contributed Perl Documentation INTERP(3)NAMEPDL::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);
FUNCTIONSinit()
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 = $spl->integ($a,$b,$opt);
Example:
my $res = $spl->integ($a,$b)
$res = $spl->integ($a,$b,{Extrapolate => 0}) #same as above
# silently comply if $a or $b are out of range
$res = $spl->eval($a,$b,{Extrapolate => 1})
BUGS
Feedback is welcome.
SEE ALSO
PDL
The GSL documentation is online at
http://sources.redhat.com/gsl/ref/gsl-ref_toc.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 v5.14.1 2011-07-26 INTERP(3)
