NAME

SYNOPSIS

    my $covariance = covariance( [1,2,3], [1,2,3] );

Or this way:

    my $v1  = vector(1,2,3);
    my $v2  = vector(1,2,3);
    my $cov = cov($v1,$v2);

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

    print "The covariance between $v1 and $v2: $covariance\n";
    my $cq = $cov->query;
    my $c0 = 0+$cov;

Create a 20 point "moving" covariance like so:

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

    my $sth = $dbh->prepare("select col1,col2 from data where something");
    my $len = 20;
    my $cov = cov();
       $cov->set_size($len);

    $sth->execute or die $dbh->errstr;
    $sth->bind_columns( my ($lhs, $rhs) ) or die $dbh->errstr;

    my $count = $len;
    while( $sth->fetch ) {
        $cov->insert( $lhs, $rhs );
        if( defined( my $c = $cov->query ) ) {
            print "Covariance: $c\n";
        }

        # This would also work:
        # print "Covariance: $cov\n" if $cov->query_filled;
    }

METHODS

new()

Create a new Statistics::Basic::Covariance object. This function takes two arguments -- which can either be arrayrefs or Statistics::Basic::Vector objects. This function is called when the covariance() shortcut-function is called.

query_vector1()

Return the Statistics::Basic::Vector for the first vector.

query_vector2()

Return the Statistics::Basic::Vector object for the second vector.

query_mean1()

Returns the Statistics::Basic::Mean object for the first vector.

query_mean2()

Returns the Statistics::Basic::Mean object for the second vector.

OVERLOADS

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

AUTHOR

COPYRIGHT

SEE ALSO