DIFF(3) User Contributed Perl Documentation DIFF(3)NAMEPDL::GSL::DIFF - PDL interface to numerical differentiation routines in
GSL
DESCRIPTION
This is an interface to the numerical differentiation package present
in the GNU Scientific Library.
SYNOPSIS
use PDL;
use PDL::GSL::DIFF;
my $x0 = 3.3;
my @res = gsldiff(\&myfunction,$x0);
# same as above:
@res = gsldiff(\&myfunction,$x0,{Method => 'central'});
# use only values greater than $x0 to get the derivative
@res = gsldiff(\&myfunction,$x0,{Method => 'forward'});
# use only values smaller than $x0 to get the derivative
@res = gsldiff(\&myfunction,$x0,{Method => 'backward'});
sub myfunction{
my ($x) = @_;
return $x**2;
}
FUNCTIONSgsldiff()
This functions serves as an interface to the three differentiation
functions present in GSL: gsl_diff_central, gsl_diff_backward and
gsl_diff_forward. To compute the derivative, the central method uses
values greater and smaller than the point at which the derivative is to
be evaluated, while backward and forward use only values smaller and
greater respectively. gsldiff() returns both the derivative and an
absolute error estimate. The default method is 'central', others can
be specified by passing an option.
Please check the GSL documentation for more information.
Usage:
($d,$abserr) = gsldiff($function_ref,$x,{Method => $method});
Example:
#derivative using default method ('central')
($d,$abserr) = gsldiff(\&myf,3.3);
#same as above with method set explicitly
($d,$abserr) = gsldiff(\&myf,3.3,{Method => 'central'});
#using backward & forward methods
($d,$abserr) = gsldiff(\&myf,3.3,{Method => 'backward'});
($d,$abserr) = gsldiff(\&myf,3.3,{Method => 'forward'});
sub myf{
my ($x) = @_;
return exp($x);
}
BUGS
Feedback is welcome. Log bugs in the PDL bug database (the database is
always linked from <http://pdl.perl.org>).
SEE ALSO
PDL
The GSL documentation is online at
http://www.gnu.org/software/gsl/manual/
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 differentiation routines were written by David Morrison.
FUNCTIONS
diff_central
Signature: (double x(); double [o] res(); double [o] abserr(); SV* funcion)
info not available
diff_central does not process bad values. It will set the bad-value
flag of all output piddles if the flag is set for any of the input
piddles.
diff_backward
Signature: (double x(); double [o] res(); double [o] abserr(); SV* funcion)
info not available
diff_backward does not process bad values. It will set the bad-value
flag of all output piddles if the flag is set for any of the input
piddles.
diff_forward
Signature: (double x(); double [o] res(); double [o] abserr(); SV* funcion)
info not available
diff_forward does not process bad values. It will set the bad-value
flag of all output piddles if the flag is set for any of the input
piddles.
perl v5.18.1 2014-01-17 DIFF(3)
