#! /usr/bin/env perl
#
# $Id: x26.pl 11730 2011-04-29 22:16:08Z huntd $
#
# -*- coding: utf-8; -*-
#
# Demo x26 for the PLplot PDL binding
#
# Multi-lingual version of the first page of example 4.
#
# Copyright (C) 2006 Alan Irwin
# Copyright (C) 2006 Andrew Ross
#
# Thanks to the following for providing translated strings for this example:
# Valery Pipin (Russian)
#
# This file is part of PLplot.
#
# PLplot is free software; you can redistribute it and/or modify
# it under the terms of the GNU Library General Public License as published
# by the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# PLplot 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 Library General Public License for more details.
#
# You should have received a copy of the GNU Library General Public License
# along with PLplot; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
# This example designed just for devices (e.g., psttfc and the
# cairo-related devices) that use the pango and fontconfig libraries. The
# best choice of glyph is selected by fontconfig and automatically rendered
# by pango in way that is sensitive to complex text layout (CTL) language
# issues for each unicode character in this example. Of course, you must
# have the appropriate TrueType fonts installed to have access to all the
# required glyphs.
# Translation instructions: The strings to be translated are given by
# x_label, y_label, alty_label, title_label, and line_label below. The
# encoding used must be UTF-8.
# The following strings to be translated involve some scientific/mathematical
# jargon which is now discussed further to help translators.
# (1) dB is a decibel unit, see http://en.wikipedia.org/wiki/Decibel .
# (2) degrees is an angular measure, see
# http://en.wikipedia.org/wiki/Degree_(angle) .
# (3) low-pass filter is one that transmits (passes) low frequencies.
# (4) pole is in the mathematical sense, see
# http://en.wikipedia.org/wiki/Pole_(complex_analysis) . "Single Pole"
# means a particular mathematical transformation of the filter function has
# a single pole, see
# http://ccrma.stanford.edu/~jos/filters/Pole_Zero_Analysis_I.html .
# Furthermore, a single-pole filter must have an inverse square decline
# (or -20 db/decade). Since the filter plotted here does have that
# characteristic, it must by definition be a single-pole filter, see also
# http://www-k.ext.ti.com/SRVS/Data/ti/KnowledgeBases/analog/document/faqs/1p.htm
# (5) decade represents a factor of 10, see
# http://en.wikipedia.org/wiki/Decade_(log_scale) .
# SYNC: x26c.c 1.1
use PDL;
use PDL::Graphics::PLplot;
use Math::Trig qw [pi];
use Getopt::Long;
@x_label = (
"Frequency",
"Частота"
);
@y_label = (
"Amplitude (dB)",
"Амплитуда (dB)"
);
@alty_label = (
"Phase shift (degrees)",
"Фазовый сдвиг (градусы)"
);
@legend_text = (
[ "Amplitude", "Phase shift" ],
[ "Амплитуда", "Фазовый сдвиг" ],
);
@title_label = (
"Single Pole Low-Pass Filter",
"Однополюсный Низко-Частотный Фильтр"
);
@line_label = (
"-20 dB/decade",
"-20 dB/десяток"
);
sub main {
# Parse and process command line arguments
plParseOpts (\@ARGV, PL_PARSE_SKIP | PL_PARSE_NOPROGRAM);
# Initialize plplot
plinit();
plfont(2);
# Make log plots using two different styles.
for (my $i=0; $i<scalar(@x_label); $i++) {
plot1(0, $x_label[$i], $y_label[$i], $alty_label[$i],
$legend_text[$i], $title_label[$i], $line_label[$i]);
}
plend();
}
sub plot1 {
my ($type, $x_label, $y_label, $alty_label, $legend_text, $title_label, $line_label) = @_;
pladv(0);
# Set up data for log plot
my $f0 = 1.0;
my $freql = -2.0 + sequence(101)/20.0;
my $freq = 10**$freql;
my $ampl = 20.0 * log10(1.0 / sqrt(1.0 + ($freq / $f0)**2));
my $phase = -(180.0 / pi) * atan($freq / $f0);
plvpor(0.15, 0.85, 0.1, 0.9);
plwind(-2.0, 3.0, -80.0, 0.0);
# Try different axis and labelling styles.
plcol0(1);
if ($type == 0) {
plbox(0.0, 0,0.0, 0, "bclnst", "bnstv");
}
if ($type == 1) {
plbox(0.0, 0, 0.0, 0, "bcfghlnst", "bcghnstv");
}
# Plot ampl vs freq
plcol0(2);
plline($freql, $ampl);
plcol0(2);
plptex(1.6, -30.0, 1.0, -20.0, 0.5, $line_label);
# Put labels on
plcol0(1);
plmtex(3.2, 0.5, 0.5, "b", $x_label);
plmtex(2.0, 0.5, 0.5, "t", $title_label);
plcol0(2);
plmtex(5.0, 0.5, 0.5, "l", $y_label);
# For the gridless case, put phase vs freq on same plot
if ($type == 0) {
plcol0(1);
plwind(-2.0, 3.0, -100.0, 0.0);
plbox(0.0, 0, 30.0, 3, "", "cmstv");
plcol0(3);
plline($freql, $phase);
plstring($freql, $phase, "*");
plcol0(3);
plmtex(5.0, 0.5, 0.5, "r", $alty_label);
}
# Draw a legend
my @opt_array = (PL_LEGEND_LINE, PL_LEGEND_LINE | PL_LEGEND_SYMBOL);
my @text_colors = (2, 3);
my @text = ("Amplitude", "Phase shift");
my @line_colors = (2, 3);
my @line_styles = (1, 1);
my @line_widths = (1, 1);
my @symbol_colors = (3, 3); # ???
my @symbol_scales = (1, 1); # ???
my @symbol_numbers = (4, 4);# ???
my @symbols = ('*', '*'); # ???
plscol0a(15, 32, 32, 32, 0.70);
my ($legend_width, $legend_height) = pllegend(
PL_LEGEND_BACKGROUND | PL_LEGEND_BOUNDING_BOX, 0,
0.0, 0.0, 0.1, 15,
1, 1, 0, 0,
$nlegend = 2, \@opt_array,
1.0, 1.0, 2.0,
1., \@text_colors, $legend_text,
0, 0, 0, 0,
\@line_colors, \@line_styles, \@line_widths,
\@symbol_colors, \@symbol_scales, \@symbol_numbers, \@symbols);
}
main();