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# $Id: xw04.py 12323 2013-05-02 17:41:54Z airwin $
# Copyright (C) 2001-1010 Alan W. Irwin
# Log plot demo.
#
# 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
#
from plplot_py_demos import *
# main
#
# Illustration of logarithmic axes, and redefinition of window.
def main():
plfont(2)
plot1(0)
plot1(1)
# Restore defaults
plfont(1)
#plcol0(1)
def plot1(type):
pladv(0)
f0 = 1.0
freql = -2.0 + arange(101)/20.0
freq = pow(10.0, freql)
ampl = 20.0 * log10(1.0 / sqrt(1.0 + pow((freq / f0), 2.)))
phase = -(180.0 / pi) * arctan(freq / f0)
plvpor(0.15, 0.85, 0.1, 0.9)
plwind(-2., 3.0, -80.0, 0.0)
plcol0(1)
if type == 0:
plbox("bclnst", 0.0, 0, "bnstv", 0.0, 0)
elif type == 1:
plbox("bcfghlnst", 0.0, 0, "bcghnstv", 0.0, 0)
else:
print "error: type must be either 0 or 1"
plcol0(2)
plline(freql, ampl)
plcol0(2)
plptex(1.6, -30.0, 1.0, -20.0, 0.5, "-20 dB/decade")
# Put labels on
plcol0(1)
plmtex("b", 3.2, 0.5, 0.5, "Frequency")
plmtex("t", 2.0, 0.5, 0.5, "Single Pole Low-Pass Filter")
plcol0(2)
plmtex("l", 5.0, 0.5, 0.5, "Amplitude (dB)")
# 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, "cmstv", 30.0, 3)
plcol0(3)
plline(freql, phase)
plstring(freql, phase, "*")
plcol0(3)
plmtex("r", 5.0, 0.5, 0.5, "Phase shift (degrees)")
nlegend = 2
else:
nlegend = 1
# Draw a legend.
# Set up legend arrays with the correct size, type.
opt_array = zeros(nlegend, "int")
text_colors = zeros(nlegend, "int")
text = zeros(nlegend, "S20")
box_colors = zeros(nlegend, "int")
box_patterns = zeros(nlegend, "int")
box_scales = zeros(nlegend)
box_line_widths = zeros(nlegend)
line_colors = zeros(nlegend, "int")
line_styles = zeros(nlegend, "int")
line_widths = zeros(nlegend)
symbol_colors = zeros(nlegend, "int")
symbol_scales = zeros(nlegend)
symbol_numbers = zeros(nlegend, "int")
symbols = zeros(nlegend, "S10")
# Only specify legend data that are required according to the
# value of opt_array for that entry.
# Data for first legend entry.
opt_array[0] = PL_LEGEND_LINE
text_colors[0] = 2
text[0] = "Amplitude"
line_colors[0] = 2
line_styles[0] = 1
line_widths[0] = 1.
# Data for second legend entry.
if nlegend > 1:
opt_array[1] = PL_LEGEND_LINE | PL_LEGEND_SYMBOL
text_colors[1] = 3
text[1] = "Phase shift"
line_colors[1] = 3
line_styles[1] = 1
line_widths[1] = 1.
symbol_colors[1] = 3
symbol_scales[1] = 1.
symbol_numbers[1] = 4
symbols[1] = "*"
plscol0a( 15, 32, 32, 32, 0.70 )
(legend_width, legend_height) = \
pllegend( PL_LEGEND_BACKGROUND | PL_LEGEND_BOUNDING_BOX, 0, 0.0, 0.0,
0.1, 15, 1, 1, 0, 0, opt_array, 1.0, 1.0, 2.0,
1., text_colors, text,
box_colors, box_patterns, box_scales, box_line_widths,
line_colors, line_styles, line_widths,
symbol_colors, symbol_scales, symbol_numbers, symbols )
main()
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