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107 lines
2.7 KiB
Lua
107 lines
2.7 KiB
Lua
--[[ $Id: x04.lua 9414 2009-01-29 22:48:54Z airwin $
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Log plot demo.
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Simple line plot and multiple windows demo.
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Copyright (C) 2008 Werner Smekal
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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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-- initialise Lua bindings for PLplot examples.
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dofile("plplot_examples.lua")
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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(type)
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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 type == 0 then
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pl.box("bclnst", 0, 0, "bnstv", 0, 0)
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end
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if type == 1 then
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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, "-20 dB/decade")
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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, "Frequency")
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pl.mtex("t", 2, 0.5, 0.5, "Single Pole Low-Pass Filter")
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pl.col0(2)
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pl.mtex("l", 5, 0.5, 0.5, "Amplitude (dB)")
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-- For the gridless case, put phase vs freq on same plot
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if type == 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, "Phase shift (degrees)")
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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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plot1(0)
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plot1(1)
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pl.plend()
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