1Statistics::Basic::CovaUrsiearncCeo(n3t)ributed Perl DocSutmaetnitsattiicosn::Basic::Covariance(3)
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NAME

6       Statistics::Basic::Covariance - find the covariance between two lists
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SYNOPSIS

9       Invoke it this way:
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11           my $covariance = covariance( [1,2,3], [1,2,3] );
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13       Or this way:
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15           my $v1  = vector(1,2,3);
16           my $v2  = vector(1,2,3);
17           my $cov = cov($v1,$v2);
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19       And then either query the values or print them like so:
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21           print "The covariance between $v1 and $v2: $covariance\n";
22           my $cq = $cov->query;
23           my $c0 = 0+$cov;
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25       Create a 20 point "moving" covariance like so:
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27           use Statistics::Basic qw(:all nofill);
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29           my $sth = $dbh->prepare("select col1,col2 from data where something");
30           my $len = 20;
31           my $cov = cov();
32              $cov->set_size($len);
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34           $sth->execute or die $dbh->errstr;
35           $sth->bind_columns( my ($lhs, $rhs) ) or die $dbh->errstr;
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37           my $count = $len;
38           while( $sth->fetch ) {
39               $cov->insert( $lhs, $rhs );
40               if( defined( my $c = $cov->query ) ) {
41                   print "Covariance: $c\n";
42               }
43
44               # This would also work:
45               # print "Covariance: $cov\n" if $cov->query_filled;
46           }
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METHODS

49       This list of methods skips the methods inherited from
50       Statistics::Basic::_TwoVectorBase (things like query(), insert(), and
51       ginsert()).
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53       new()
54           Create a new Statistics::Basic::Covariance object.  This function
55           takes two arguments -- which can either be arrayrefs or
56           Statistics::Basic::Vector objects.  This function is called when
57           the covariance() shortcut-function is called.
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59       query_vector1()
60           Return the Statistics::Basic::Vector for the first vector.
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62       query_vector2()
63           Return the Statistics::Basic::Vector object for the second vector.
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65       query_mean1()
66           Returns the Statistics::Basic::Mean object for the first vector.
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68       query_mean2()
69           Returns the Statistics::Basic::Mean object for the second vector.
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OVERLOADS

72       This object is overloaded.  It tries to return an appropriate string
73       for the calculation or the value of the computation in numeric context.
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75       In boolean context, this object is always true (even when empty).
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AUTHOR

78       Paul Miller "<jettero@cpan.org>"
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81       Copyright 2009 Paul Miller -- Licensed under the LGPL
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SEE ALSO

84       perl(1), Statistics::Basic, Statistics::Basic::_TwoVectorBase,
85       Statistics::Basic::Vector
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89perl v5.12.3                      2009-06-28  Statistics::Basic::Covariance(3)
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