From 81512340bb09d482912b3bf69a955d18b0cb2a78 Mon Sep 17 00:00:00 2001
From: Jonathan Leto <leto@kadath.local>
Date: Thu, 9 Oct 2008 20:46:46 -0700
Subject: [PATCH] Improved intro examples in Math::GSL and fixed return
 signature of gsl_deriv_* functions

---
 Changes         |  2 ++
 Deriv.i         | 18 +++++++++++-------
 lib/Math/GSL.pm | 15 ++++++++++++---
 t/Deriv.t       | 30 +++++++++++++-----------------
 4 files changed, 38 insertions(+), 27 deletions(-)

diff --git a/Changes b/Changes
index 5ed0921..6c808eb 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,7 @@
 0.14
     - Improved Roots docs
+    - Improved introduction examples in Math::GSL
+    - Fixed return signature of gsl_deriv_* functions to return a flat list
     - Fix location of shared objects (Sisyphus)
     - Added raw() method to RNG objects
     - Chebyshev Series Approximation, with tests and docs
diff --git a/Deriv.i b/Deriv.i
index e00e89a..eac03aa 100644
--- a/Deriv.i
+++ b/Deriv.i
@@ -7,7 +7,7 @@
                        double x, double h,
                        double *result, double *abserr) {
     SV ** sv;
-    AV* av = newAV();
+    //AV* av = newAV();
 
     sv = hv_fetch(Callbacks, (char*)&$input, sizeof($input), FALSE );
     if (sv == (SV**)NULL)
@@ -22,13 +22,18 @@
     /* This actually calls the perl subroutine */
     call_sv(*sv, G_SCALAR);    
 
-    av_push(av, newSVnv((double) *$4));
-    av_push(av, newSVnv((double) *$5));
-    $result = sv_2mortal( newRV_noinc( (SV*) av) );
+    //av_push(av, newSVnv((double) *$4));
+    //av_push(av, newSVnv((double) *$5));
+    //$result = sv_2mortal( newRV_noinc( (SV*) av) );
+    $result = sv_newmortal();
+    sv_setnv($result, (double) *$4);
+    argvi++;
+    sv_setnv($result, (double) *$5);
+    argvi++;
+
     if (argvi >= items) {            
         EXTEND(SP,1);              
     }
-    argvi++;
 
 }
 
@@ -55,11 +60,10 @@ __END__
 
 =head1 NAME
 
-Math::GSL::Deriv - Functions to compute numerical derivatives by finite differencing
+Math::GSL::Deriv - Numerical Derivatives
 
 =head1 SYNOPSIS
 
-This module is not yet implemented. Patches Welcome!
 
 use Math::GSL::Deriv qw /:all/;
 
diff --git a/lib/Math/GSL.pm b/lib/Math/GSL.pm
index 496ad22..dbc18bd 100644
--- a/lib/Math/GSL.pm
+++ b/lib/Math/GSL.pm
@@ -39,13 +39,22 @@ Version 0.13_01
 
 =head1 SYNOPSIS
 
-    use Math::GSL::Matrix qw/:all/;
+    use Math::GSL::Matrix;
     my $matrix = Math::GSL::Matrix->new(5,5);   # 5x5 zero matrix
-    $matrix->set_col(0, [1..5])
-           ->set_row(2, [5..9]);
+    # note that columns and rows are zero-based
+    $matrix->set_col(0, [1..5])                 # set *first* column to 1,2,3,4,5
+           ->set_row(2, [5..9]);                # set *third* column to 5,6,7,8,9   
     my @matrix = $matrix->as_list;              # matrix as Perl list
     my $gsl_matrix = $matrix->raw;              # underlying GSL object
 
+    use Math::GSL::RNG;
+    my $rng = Math::GSL::RNG->new;
+    my @random_numbers = map { $rng->get } (1 .. 1000);
+
+    use Math::GSL::Deriv qw/:all/;
+    my $function = sub { my $x=shift; sin($x**2) };
+    my ($status,$val,$err) = gsl_deriv_central($function, 5, 0.01 );
+
 Each GSL subsystem has it's own module. For example, the random number generator
 subsystem is Math::GSL::RNG. Many subsystems have a more Perlish and
 object-oriented frontend which can be used, as the above example shows. The raw
diff --git a/t/Deriv.t b/t/Deriv.t
index a0a68a7..15d80cd 100644
--- a/t/Deriv.t
+++ b/t/Deriv.t
@@ -34,41 +34,37 @@ sub TEST_DERIV_CENTRAL_DIES : Tests {
 }
 
 sub TEST_DERIV_CENTRAL : Tests { 
-    my ($x,$h)=(10,0.01);
     my $self = shift;
-    my ($status, $result);
+    my ($x,$h)=(10,0.01);
 
-    ($status, $result) = gsl_deriv_central ( sub { $_[0] ** 3 }, $x, $h,); 
+    my ($status, $val,$err) = gsl_deriv_central ( sub { $_[0] ** 3 }, $x, $h,); 
     ok_status($status);
-    my $res = abs($result->[0]-3*$x**2);
-    ok( $res < $result->[1] , sprintf ("gsl_deriv_forward: res=%.18f, abserr=%.18f",$res, $result->[1] ));
+    my $res = abs($val-3*$x**2);
+    ok( $res <= $err  , sprintf ("gsl_deriv_forward: res=%.18f, abserr=%.18f",$res, $err ));
 }
 
 sub TEST_DERIV_FORWARD : Tests { 
-    my ($x,$h)=(10,0.01);
     my $self = shift;
-    my ($status, $result);
 
-    ($status, $result) = gsl_deriv_forward ( sub { 2 * $_[0] ** 2 }, $x, $h,); 
+    my ($x,$h)=(10,0.01);
+    my ($status, $val,$err) = gsl_deriv_forward ( sub { 2 * $_[0] ** 2 }, $x, $h,); 
     ok_status($status);
-    my $res = abs($result->[0]-4*$x);
-    ok( $res < $result->[1] , sprintf ("gsl_deriv_forward: res=%.18f, abserr=%.18f",$res, $result->[1] ));
+    my $res = abs($val-4*$x);
+    ok( $res <= $err , sprintf ("gsl_deriv_forward: res=%.18f, abserr=%.18f",$res, $err ));
 }
 
 sub TEST_DERIV_BACKWARD : Tests { 
-    my ($x,$h)=(10,0.01);
     my $self = shift;
-    my ($status, $result);
-
-    ($status, $result) = gsl_deriv_backward ( sub { log $_[0] }, $x, $h,); 
+    my ($x,$h)=(10,0.01);
+    my ($status, $val, $err) = gsl_deriv_backward ( sub { log $_[0] }, $x, $h,); 
     ok_status($status);
-    my $res = abs($result->[0]-1/$x);
-    ok( $res < $result->[1] , sprintf ("gsl_deriv_backward: res=%.18f, abserr=%.18f",$res, $result->[1] ));
+    my $res = abs($val-1/$x);
+    ok( $res <= $err , sprintf ("gsl_deriv_backward: res=%.18f, abserr=%.18f",$res, $err ));
 }
 
 sub TEST_DERIV_CENTRAL_CALLS_THE_SUB : Tests { 
-    my ($x,$h)=(10,0.01);
     my $self = shift;
+    my ($x,$h)=(10,0.01);
 
     throws_ok( sub {
                 gsl_deriv_central ( sub { die "CALL ME BACK!"} , $x, $h)