NAME
Finance::Shares::on_balance_volume - Indicate direction of trades
SYNOPSIS
Two examples of how to specify a on_balance_volume line, one showing the minimum required and the other illustrating all the possible fields.
use Finance::Shares::Model;
use Finance::Shares::on_balance_volume;
my @spec = (
...
lines => [
...
minimal => {
function => 'on_balance_volume',
},
full = {
function => 'on_balance_volume',
key => 'on balance volume',
style => { ... },
shown => 1,
order => -99,
},
...
],
...
samples => [
...
one => {
lines => ['full', 'minimal'],
...
}
],
);
my $fsm = new Finance::Shares::Model( @spec );
$fsm->build();DESCRIPTION
This line attempts to interpret the volume of trades as an ebb and flow. It is assumed that when the closing price is higher than the previous day, the volume was buying, and that selling is happening if the price is falling.
Although a gross simplification, it is still a useful approximation.
The results are normally displayed on an 'analysis' graph as the changes may be positive or negative values. WARNING: if you specify a graph for the on_balance_volume line, it will NOT relate to the Y axis. '0' will probably be around the middle (vertically) of the on_balance_volume line, while for the Y axis, '0' may well be below the bottom of the page.
To get the line to appear, there must be an entry within the lines block of a Finance::Shares::Model specification. This hash ref must have a function field with the value on_balance_volume. The entry's tag must then appear in the line field of a sample.
There are no significant options.
OPTIONS
function
Required. Must be on_balance_volume.
key
Most functions generate suitable (if lengthy) entries. This provides the opportunity to identify the line in the Key panel, next to the style.
order
The entries on the graph are sorted according to this value, which defaults to the order required for calculation. A large integer will bring the line to the front and a negative number will put it behind all the rest.
Examples
- -1
-
The line goes behind the data.
- 0.5
-
In front of the data, but only just.
- 999
-
Probably the top line.
shown
1 for the line to be shown, 0 hides it. (Default: 1)
style
This is normally a hash ref defining the data's appearance. See PostScript::Graph::Style for full details, or "Lines" in Finance::Shares::Model for an example.
BUGS
Please let me know when you suspect something isn't right. A short script working from a CSV file demonstrating the problem would be very helpful.
AUTHOR
Chris Willmot, chris@willmot.org.uk
LICENCE
Copyright (c) 2002-2003 Christopher P Willmot
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. A copy can be found at http://www.gnu.org/copyleft/gpl.html
SEE ALSO
Finance::Shares::Overview provides an introduction to the suite, and fsmodel is the principal script.
Modules involved in processing the model include Finance::Shares::Model, Finance::Shares::MySQL, Finance::Shares::Chart. Chart and file details may be found in PostScript::File, PostScript::Graph::Paper, PostScript::Graph::Key, PostScript::Graph::Style.
All functions are invoked from their own modules, all with lower-case names such as Finance::Shares::moving_average. The nitty-gritty on how to write each line specification are found there.
The quote data is stored in a Finance::Shares::data object. For information on writing additional line functions see Finance::Share::Function and Finance::Share::Line. Also, Finance::Share::test covers writing your own tests.
1 POD Error
The following errors were encountered while parsing the POD:
- Around line 178:
Expected text after =item, not a number