Root/nanonote-files/example-files/data/Examples/lua-plplot-examples/x04.lua

1--[[ $Id: x04.lua 9414 2009-01-29 22:48:54Z airwin $
2
3    Log plot demo.
4    Simple line plot and multiple windows demo.
5
6  Copyright (C) 2008 Werner Smekal
7
8  This file is part of PLplot.
9
10  PLplot is free software you can redistribute it and/or modify
11  it under the terms of the GNU General Library Public License as published
12  by the Free Software Foundation either version 2 of the License, or
13  (at your option) any later version.
14
15  PLplot is distributed in the hope that it will be useful,
16  but WITHOUT ANY WARRANTY without even the implied warranty of
17  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18  GNU Library General Public License for more details.
19
20  You should have received a copy of the GNU Library General Public License
21  along with PLplot if not, write to the Free Software
22  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23--]]
24
25-- initialise Lua bindings for PLplot examples.
26dofile("plplot_examples.lua")
27
28----------------------------------------------------------------------------
29-- plot1
30--
31-- Log-linear plot.
32----------------------------------------------------------------------------
33
34function plot1(type)
35  freql = {}
36  ampl = {}
37  phase = {}
38
39  pl.adv(0)
40
41  -- Set up data for log plot
42  f0 = 1
43  for i=1, 101 do
44    freql[i] = -2 + (i-1) / 20
45    freq = 10^freql[i]
46    ampl[i] = 20 * math.log10(1 / math.sqrt(1 + (freq / f0)^2))
47    phase[i] = -(180 / math.pi) * math.atan(freq / f0)
48  end
49
50  pl.vpor(0.15, 0.85, 0.1, 0.9)
51  pl.wind(-2, 3, -80, 0)
52
53  -- Try different axis and labelling styles.
54  pl.col0(1)
55  if type == 0 then
56    pl.box("bclnst", 0, 0, "bnstv", 0, 0)
57  end
58  
59  if type == 1 then
60    pl.box("bcfghlnst", 0, 0, "bcghnstv", 0, 0)
61  end
62  
63  -- Plot ampl vs freq
64  pl.col0(2)
65  pl.line(freql, ampl)
66  pl.col0(1)
67  pl.ptex(1.6, -30, 1, -20, 0.5, "-20 dB/decade")
68
69  -- Put labels on
70  pl.col0(1)
71  pl.mtex("b", 3.2, 0.5, 0.5, "Frequency")
72  pl.mtex("t", 2, 0.5, 0.5, "Single Pole Low-Pass Filter")
73  pl.col0(2)
74  pl.mtex("l", 5, 0.5, 0.5, "Amplitude (dB)")
75
76  -- For the gridless case, put phase vs freq on same plot
77  if type == 0 then
78    pl.col0(1)
79    pl.wind(-2, 3, -100, 0)
80    pl.box("", 0, 0, "cmstv", 30, 3)
81    pl.col0(3)
82    pl.line(freql, phase)
83    pl.col0(3)
84    pl.mtex("r", 5, 0.5, 0.5, "Phase shift (degrees)")
85  end
86end
87
88
89----------------------------------------------------------------------------
90-- main
91--
92-- Illustration of logarithmic axes, and redefinition of window.
93----------------------------------------------------------------------------
94
95-- Parse and process command line arguments
96pl.parseopts(arg, pl.PL_PARSE_FULL)
97
98-- Initialize plplot
99pl.init()
100pl.font(2)
101
102-- Make log plots using two different styles.
103plot1(0)
104plot1(1)
105
106pl.plend()
107

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