NAME
Finance::Shares::percent_band - Calculate a Bollinger band
SYNOPSIS
Two examples of how to specify a Bollinger band, one showing the minimum required and the other illustrating all the possible fields.
use Finance::Shares::Model;
use Finance::Shares::percent_band;
my @spec = (
...
lines => [
...
minimal => {
function => 'percent_band',
},
full = {
function => 'percent_band',
graph => 'Stock Prices',
gtype => 'price',
line => 'some_line',
percent => 3,
style => { ... },
shown => 1,
order => -99,
},
...
],
samples => [
...
one => {
lines => ['full', 'minimal'],
...
}
],
);
my $fsm = new Finance::Shares::Model( @spec );
$fsm->build();DESCRIPTION
Boundary lines are drawn a fixed percentage above and below the source line.
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 percent_band. The entry's tag must then appear in the line field of a sample.
The other main fields are line and percent.
OPTIONS
function
Required. Must be percent_band.
graph
If present, this should be a tag declared as a charts resource. It identifies a particular graph within a chart page. A gtype is implied. (No default)
This should be the graph where line appears.
gtype
Required, unless graph is given. This specifies the type of graph the function lines should appear on. It should be one of price, volume, analysis or level. (Default: price)
This should be the gtype for line.
line
Identifies the source line at the centre of the band. (Default: 'close')
percent
The boundary lines are this percentage value above and below the source line.
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.
Not so much bugs but temporary infecilities due to the difficulties of controlling two lines from one specification. No user key is available and it is not possible to have complete control of the style unless one of the lines dissappears from the Key.
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 189:
Expected text after =item, not a number