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GNU Scientific Library 1.12 (Default branch)
12-30-2008
The GNU Scientific Library (GSL) is a collection of routines for numerical computing. The routines are written from scratch by the GSL team in ANSI C, and present a modern API for C programmers, while allowing wrappers to be written for very high-level languages. License: GNU General Public License v3 Changes:|
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DIFF(3pm) User Contributed Perl Documentation DIFF(3pm) NAME
PDL::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 $x**2; } FUNCTIONS
gsldiff() This functions serves as an interface to the three differentiation functions present in GSL: gsl_diff_central, gsl_diff_backward and gsl_diff_forward. To compute the derivative, the central method uses values greater and smaller than the point at which the derivative is to be evaluated, while backward and forward use only values smaller and greater respectively. gsldiff() returns both the derivative and an absolute error estimate. The default method is 'central', others can be specified by passing an option. Please check the GSL documentation for more information. Usage: ($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://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 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 v5.14.2 2012-05-30 DIFF(3pm)