# $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()