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152 lines
5.0 KiB
Lua
152 lines
5.0 KiB
Lua
--[[ -*- coding: utf-8 -*-
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$Id: x26.lua 9506 2009-02-11 08:23:29Z smekal $
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Multi-lingual version of the first page of example 4.
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Copyright (C) 2009 Werner Smekal
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Thanks to the following for providing translated strings for this example:
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Valery Pipin (Russian)
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This file is part of PLplot.
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PLplot is free software you can redistribute it and/or modify
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it under the terms of the GNU General Library Public License as published
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by the Free Software Foundation either version 2 of the License, or
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(at your option) any later version.
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PLplot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Library General Public License for more details.
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You should have received a copy of the GNU Library General Public License
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along with PLplot if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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--]]
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--[[
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This example designed just for devices (e.g., psttfc and the
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cairo-related devices) that use the pango and fontconfig libraries. The
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best choice of glyph is selected by fontconfig and automatically rendered
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by pango in way that is sensitive to complex text layout (CTL) language
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issues for each unicode character in this example. Of course, you must
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have the appropriate TrueType fonts installed to have access to all the
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required glyphs.
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Translation instructions: The strings to be translated are given by
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x_label, y_label, alty_label, title_label, and line_label below. The
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encoding used must be UTF-8.
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The following strings to be translated involve some scientific/mathematical
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jargon which is now discussed further to help translators.
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(1) dB is a decibel unit, see http://en.wikipedia.org/wiki/Decibel .
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(2) degrees is an angular measure, see
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http://en.wikipedia.org/wiki/Degree_(angle) .
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(3) low-pass filter is one that transmits (passes) low frequencies.
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(4) pole is in the mathematical sense, see
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http://en.wikipedia.org/wiki/Pole_(complex_analysis) . "Single Pole"
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means a particular mathematical transformation of the filter function has
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a single pole, see
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http://ccrma.stanford.edu/~jos/filters/Pole_Zero_Analysis_I.html .
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Furthermore, a single-pole filter must have an inverse square decline
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(or -20 db/decade). Since the filter plotted here does have that
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characteristic, it must by definition be a single-pole filter, see also
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http://www-k.ext.ti.com/SRVS/Data/ti/KnowledgeBases/analog/document/faqs/1p.htm
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(5) decade represents a factor of 10, see
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http://en.wikipedia.org/wiki/Decade_(log_scale) .
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--]]
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-- initialise Lua bindings for PLplot examples.
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dofile("plplot_examples.lua")
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x_label = { "Frequency", "Частота" }
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y_label = { "Amplitude (dB)", "Амплитуда (dB)" }
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alty_label = { "Phase shift (degrees)", "Фазовый сдвиг (градусы)" }
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title_label = { "Single Pole Low-Pass Filter", "Однополюсный Низко-Частотный Фильтр" }
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line_label = { "-20 dB/decade", "-20 dB/десяток" }
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----------------------------------------------------------------------------
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-- plot1
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--
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-- Log-linear plot.
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----------------------------------------------------------------------------
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function plot1(typ, x_label, y_label, alty_label, title_label, line_label)
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freql = {}
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ampl = {}
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phase = {}
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pl.adv(0)
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-- Set up data for log plot
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f0 = 1
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for i = 1, 101 do
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freql[i] = -2 + (i-1)/20
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freq = 10^freql[i]
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ampl[i] = 20 * math.log10(1/math.sqrt(1+(freq/f0)^2))
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phase[i] = -180/math.pi*math.atan(freq/f0)
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end
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pl.vpor(0.15, 0.85, 0.1, 0.9)
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pl.wind(-2, 3, -80, 0)
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-- Try different axis and labelling styles.
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pl.col0(1)
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if typ==0 then
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pl.box("bclnst", 0, 0, "bnstv", 0, 0)
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else
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pl.box("bcfghlnst", 0, 0, "bcghnstv", 0, 0)
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end
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-- Plot ampl vs freq
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pl.col0(2)
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pl.line(freql, ampl)
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pl.col0(1)
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pl.ptex(1.6, -30, 1, -20, 0.5, line_label)
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-- Put labels on
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pl.col0(1)
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pl.mtex("b", 3.2, 0.5, 0.5, x_label)
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pl.mtex("t", 2, 0.5, 0.5, title_label)
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pl.col0(2)
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pl.mtex("l", 5, 0.5, 0.5, y_label)
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-- For the gridless case, put phase vs freq on same plot
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if typ==0 then
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pl.col0(1)
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pl.wind(-2, 3, -100, 0)
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pl.box("", 0, 0, "cmstv", 30, 3)
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pl.col0(3)
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pl.line(freql, phase)
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pl.col0(3)
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pl.mtex("r", 5, 0.5, 0.5, alty_label)
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end
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end
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----------------------------------------------------------------------------
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-- main
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--
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-- Illustration of logarithmic axes, and redefinition of window.
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----------------------------------------------------------------------------
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-- Parse and process command line arguments
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pl.parseopts(arg, pl.PL_PARSE_FULL)
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-- Initialize plplot
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pl.init()
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pl.font(2)
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-- Make log plots using two different styles.
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for i = 1, 2 do
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plot1(0, x_label[i], y_label[i], alty_label[i], title_label[i], line_label[i])
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end
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pl.plend()
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