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Man Pages


Manual Reference Pages  -  STATISTICS::BASIC::VARIANCE (3)

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NAME

Statistics::Basic::Variance - find the variance of a list

CONTENTS

SYNOPSIS

Invoke it this way:



    my $variance = variance(1,2,3);



Or this way:



    my $v1  = vector(1,2,3);
    my $var = var($v1);



And then either query the values or print them like so:



    print "The variance of $v1: $variance\n";
    my $vq = $var->query;
    my $v0 = 0+$var;



Create a 20 point moving variance like so:



    use Statistics::Basic qw(:all nofill);

    my $sth = $dbh->prepare("select col1 from data where something");
    my $len = 20;
    my $var = var()->set_size($len);

    $sth->execute or die $dbh->errstr;
    $sth->bind_columns( my $val ) or die $dbh->errstr;

    while( $sth->fetch ) {
        $var->insert( $val );
        if( defined( my $v = $var->query ) ) {
            print "Variance: $v\n";
        }

        # This would also work:
        # print "Variance: $v\n" if $var->query_filled;
    }



METHODS

<B>B>new()<B>B> The constructor takes a list of values, a single array ref, or a single Statistics::Basic::Vector as arguments. It returns a Statistics::Basic::Variance object.

Note: normally you’d use the mean() constructor, rather than building these by hand using new().

<B>B>query_mean()<B>B> Returns the Statistics::Basic::Mean object used in the variance computation.
<B>B>_OVB::import()<B>B> This module also inherits all the overloads and methods from Statistics::Basic::_OneVectorBase.

AUTHOR

Paul Miller <jettero@cpan.org>

I am using this software in my own projects... If you find bugs, please please please let me know. :) Actually, let me know if you find it handy at all. Half the fun of releasing this stuff is knowing that people use it.

OVERLOADS

This object is overloaded. It tries to return an appropriate string for the calculation or the value of the computation in numeric context.

In boolean context, this object is always true (even when empty).

COPYRIGHT

Copyright 2012 Paul Miller — Licensed under the LGPL

SEE ALSO

perl(1), Statistics::Basic, Statistics::Basic::_OneVectorBase, Statistics::Basic::Vector
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perl v5.20.3 STATISTICS::BASIC::VARIANCE (3) 2012-01-23

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