1DIFF(3)               User Contributed Perl Documentation              DIFF(3)
2
3
4

NAME

6       PDL::GSL::DIFF - PDL interface to numerical differentiation routines in
7       GSL
8

DESCRIPTION

10       This is an interface to the numerical differentiation package present
11       in the GNU Scientific Library.
12

SYNOPSIS

14          use PDL;
15          use PDL::GSL::DIFF;
16
17          my $x0 = 3.3;
18
19          my @res = gsldiff(\&myfunction,$x0);
20          # same as above:
21          @res = gsldiff(\&myfunction,$x0,{Method => 'central'});
22
23          # use only values greater than $x0 to get the derivative
24          @res =  gsldiff(\&myfunction,$x0,{Method => 'forward'});
25
26          # use only values smaller than $x0 to get the derivative
27          @res = gsldiff(\&myfunction,$x0,{Method => 'backward'});
28
29          sub myfunction{
30            my ($x) = @_;
31            return $x**2;
32          }
33       #line 61 "DIFF.pm"
34

FUNCTIONS

36   diff_central
37         Signature: (double x(); double [o] res(); double [o] abserr(); SV* function)
38
39       info not available
40
41       diff_central does not process bad values.  It will set the bad-value
42       flag of all output ndarrays if the flag is set for any of the input
43       ndarrays.
44
45   diff_backward
46         Signature: (double x(); double [o] res(); double [o] abserr(); SV* function)
47
48       info not available
49
50       diff_backward does not process bad values.  It will set the bad-value
51       flag of all output ndarrays if the flag is set for any of the input
52       ndarrays.
53
54   diff_forward
55         Signature: (double x(); double [o] res(); double [o] abserr(); SV* function)
56
57       info not available
58
59       diff_forward does not process bad values.  It will set the bad-value
60       flag of all output ndarrays if the flag is set for any of the input
61       ndarrays.
62
63   gsldiff
64       This functions serves as an interface to the three differentiation
65       functions present in GSL: gsl_diff_central, gsl_diff_backward and
66       gsl_diff_forward. To compute the derivative, the central method uses
67       values greater and smaller than the point at which the derivative is to
68       be evaluated, while backward and forward use only values smaller and
69       greater respectively. gsldiff() returns both the derivative and an
70       absolute error estimate. The default  method is 'central', others can
71       be specified by passing an option.
72
73       Please check the GSL documentation for more information.
74
75       Usage:
76
77         ($d,$abserr) = gsldiff($function_ref,$x,{Method => $method});
78
79       Example:
80
81         #derivative using default method ('central')
82         ($d,$abserr) = gsldiff(\&myf,3.3);
83
84         #same as above with method set explicitly
85         ($d,$abserr) = gsldiff(\&myf,3.3,{Method => 'central'});
86
87         #using backward & forward methods
88         ($d,$abserr) = gsldiff(\&myf,3.3,{Method => 'backward'});
89         ($d,$abserr) = gsldiff(\&myf,3.3,{Method => 'forward'});
90
91         sub myf{
92           my ($x) = @_;
93           return exp($x);
94         }
95

BUGS

97       Feedback is welcome. Log bugs in the PDL bug database (the database is
98       always linked from <http://pdl.perl.org>).
99

SEE ALSO

101       PDL
102
103       The GSL documentation is online at
104
105         http://www.gnu.org/software/gsl/manual/
106

AUTHOR

108       This file copyright (C) 2003 Andres Jordan
109       <andresj@physics.rutgers.edu> All rights reserved. There is no
110       warranty. You are allowed to redistribute this software documentation
111       under certain conditions. For details, see the file COPYING in the PDL
112       distribution. If this file is separated from the PDL distribution, the
113       copyright notice should be included in the file.
114
115       The GSL differentiation routines were written by David Morrison.
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119perl v5.34.0                      2022-02-28                           DIFF(3)
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