=head1 NAME

Statistics::Basic::_TwoVectorBase - base class objects like Correlation

=head1 METHODS

=over 4

=item B<query()>

Query the value of the object.  It will return the undefined value until there's
something to calculate.

=item B<insert()>

Insert two new new values into the vectors.  This function must be given
precisely two arguments and probably shouldn't be undefined values in most
cases.

    # insert a 4 in one vector and a 3 in the other
    $object_instance->insert( 4, 3 );

=item B<append()> B<ginsert()>

The growing insert inserts new elements, growing the max size of the vector to
accommodate the new elements (if necessary).  This function must be given
precisely two arguments and probably shouldn't be undefined values in most
cases.

    # append a 4 in one vector and a 3 in the other
    $object_instance->ginsert( 4, 3 );

=item B<query_size()>

The current size of the vectors -- regardless of their max size (as set by
L</set_size()>).  This function returns a list, i.e.:

    my @s = $obj->query_size; # two values
    my $s = $obj->query_size; # the right hand value of the list

=item B<set_size()>

Set the maximum size for the underlying L<Statistics::Basic::Vector> objects.
This function requires two arguments.

=item B<set_vector()>

Set the vector objects used to calculate the object's value.  This function
takes two arguments -- which can either be arrayrefs or
L<Statistics::Basic::Vector> objects.  They must have the same number of
elements.

    my $v1 = vector
    my $v2 = $v1->copy;
    $example_correlation->set_vector($v1, $v2);

=back

=head1 OVERLOADS

This class provides overloads.  If evaluated as a string, it will attempt to
print a pretty value for the object (or C<n/a>, see L</query()> above).  the
resulting string can be tuned, in terms of precision, see
L<ipres|Statistics::Basic/ipres> for further information.

If evaluated as a number, it will try to return the raw result of L</query()>,
possibly turning the resulting C<undef> (if applicable) into a C<0> in the
process -- note that Perl does this C<0>-izing, not the overload.

The C<eq> and C<==> operators are also overloaded, trying to do the right thing.
Also see L<toler|Statistics::Basic/toler> for further information.

=head1 AUTHOR

Paul Miller C<< <jettero@cpan.org> >>

=head1 COPYRIGHT

Copyright 2012 Paul Miller -- Licensed under the LGPL

=head1 SEE ALSO

perl(1), L<Statistics::Basic>, L<Statistics::Basic::Vector>

=cut