Root/nanonote-files/example-files/data/Examples/lua-plplot-examples/x26.lua

1--[[ -*- coding: utf-8 -*-
2   
3   $Id: x26.lua 9506 2009-02-11 08:23:29Z smekal $
4
5   Multi-lingual version of the first page of example 4.
6
7   Copyright (C) 2009 Werner Smekal
8
9   Thanks to the following for providing translated strings for this example:
10   Valery Pipin (Russian)
11  
12   This file is part of PLplot.
13    
14   PLplot is free software you can redistribute it and/or modify
15   it under the terms of the GNU General Library Public License as published
16   by the Free Software Foundation either version 2 of the License, or
17   (at your option) any later version.
18   
19   PLplot is distributed in the hope that it will be useful,
20   but WITHOUT ANY WARRANTY without even the implied warranty of
21   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22   GNU Library General Public License for more details.
23    
24   You should have received a copy of the GNU Library General Public License
25   along with PLplot if not, write to the Free Software
26   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27--]]
28
29
30--[[
31  This example designed just for devices (e.g., psttfc and the
32  cairo-related devices) that use the pango and fontconfig libraries. The
33  best choice of glyph is selected by fontconfig and automatically rendered
34  by pango in way that is sensitive to complex text layout (CTL) language
35  issues for each unicode character in this example. Of course, you must
36  have the appropriate TrueType fonts installed to have access to all the
37  required glyphs.
38
39  Translation instructions: The strings to be translated are given by
40  x_label, y_label, alty_label, title_label, and line_label below. The
41  encoding used must be UTF-8.
42
43  The following strings to be translated involve some scientific/mathematical
44  jargon which is now discussed further to help translators.
45
46  (1) dB is a decibel unit, see http://en.wikipedia.org/wiki/Decibel .
47  (2) degrees is an angular measure, see
48      http://en.wikipedia.org/wiki/Degree_(angle) .
49  (3) low-pass filter is one that transmits (passes) low frequencies.
50  (4) pole is in the mathematical sense, see
51      http://en.wikipedia.org/wiki/Pole_(complex_analysis) . "Single Pole"
52      means a particular mathematical transformation of the filter function has
53      a single pole, see
54      http://ccrma.stanford.edu/~jos/filters/Pole_Zero_Analysis_I.html .
55      Furthermore, a single-pole filter must have an inverse square decline
56      (or -20 db/decade). Since the filter plotted here does have that
57      characteristic, it must by definition be a single-pole filter, see also
58      http://www-k.ext.ti.com/SRVS/Data/ti/KnowledgeBases/analog/document/faqs/1p.htm
59  (5) decade represents a factor of 10, see
60      http://en.wikipedia.org/wiki/Decade_(log_scale) .
61--]]
62
63-- initialise Lua bindings for PLplot examples.
64dofile("plplot_examples.lua")
65
66x_label = { "Frequency", "Частота" }
67y_label = { "Amplitude (dB)", "Амплитуда (dB)" }
68alty_label = { "Phase shift (degrees)", "Фазовый сдвиг (градусы)" }
69title_label = { "Single Pole Low-Pass Filter", "Однополюсный Низко-Частотный Фильтр" }
70line_label = { "-20 dB/decade", "-20 dB/десяток" }
71
72
73----------------------------------------------------------------------------
74-- plot1
75--
76-- Log-linear plot.
77----------------------------------------------------------------------------
78
79function plot1(typ, x_label, y_label, alty_label, title_label, line_label)
80  freql = {}
81  ampl = {}
82  phase = {}
83
84  pl.adv(0)
85
86  -- Set up data for log plot
87
88  f0 = 1
89  for i = 1, 101 do
90    freql[i] = -2 + (i-1)/20
91    freq = 10^freql[i]
92    ampl[i] = 20 * math.log10(1/math.sqrt(1+(freq/f0)^2))
93    phase[i] = -180/math.pi*math.atan(freq/f0)
94  end
95
96  pl.vpor(0.15, 0.85, 0.1, 0.9)
97  pl.wind(-2, 3, -80, 0)
98
99  -- Try different axis and labelling styles.
100  pl.col0(1)
101  if typ==0 then
102    pl.box("bclnst", 0, 0, "bnstv", 0, 0)
103  else
104    pl.box("bcfghlnst", 0, 0, "bcghnstv", 0, 0)
105  end
106
107  -- Plot ampl vs freq
108  pl.col0(2)
109  pl.line(freql, ampl)
110  pl.col0(1)
111  pl.ptex(1.6, -30, 1, -20, 0.5, line_label)
112
113  -- Put labels on
114  pl.col0(1)
115  pl.mtex("b", 3.2, 0.5, 0.5, x_label)
116  pl.mtex("t", 2, 0.5, 0.5, title_label)
117  pl.col0(2)
118  pl.mtex("l", 5, 0.5, 0.5, y_label)
119
120  -- For the gridless case, put phase vs freq on same plot
121  if typ==0 then
122    pl.col0(1)
123    pl.wind(-2, 3, -100, 0)
124    pl.box("", 0, 0, "cmstv", 30, 3)
125    pl.col0(3)
126    pl.line(freql, phase)
127    pl.col0(3)
128    pl.mtex("r", 5, 0.5, 0.5, alty_label)
129  end
130end
131
132
133----------------------------------------------------------------------------
134-- main
135--
136-- Illustration of logarithmic axes, and redefinition of window.
137----------------------------------------------------------------------------
138
139-- Parse and process command line arguments
140pl.parseopts(arg, pl.PL_PARSE_FULL)
141
142-- Initialize plplot
143pl.init()
144pl.font(2)
145
146-- Make log plots using two different styles.
147for i = 1, 2 do
148  plot1(0, x_label[i], y_label[i], alty_label[i], title_label[i], line_label[i])
149end
150
151pl.plend()
152

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