docs: def main():
      """
      NAME
          dayplot_magic.py
  
      DESCRIPTION
          makes 'day plots' (Day et al. 1977) and squareness/coercivity,
          plots 'linear mixing' curve from Dunlop and Carter-Stiglitz (2006).
            squareness coercivity of remanence (Neel, 1955) plots after
            Tauxe et al. (2002)
  
      SYNTAX
          dayplot_magic.py [command line options]
  
      OPTIONS
          -h prints help message and quits
          -f: specify input hysteresis file, default is rmag_hysteresis.txt
          -fr: specify input remanence file, default is rmag_remanence.txt
          -fmt [svg,png,jpg] format for output plots
          -sav saves plots and quits quietly
          -n label specimen names
      """
      args = sys.argv
      hyst_file, rem_file = "rmag_hysteresis.txt", "rmag_remanence.txt"
      dir_path = '.'
      verbose = pmagplotlib.verbose
      fmt = 'svg'  # default file format
      if '-WD' in args:
          ind = args.index('-WD')
          dir_path = args[ind+1]
      if "-h" in args:
          print(main.__doc__)
          sys.exit()
      if '-f' in args:
          ind = args.index("-f")
          hyst_file = args[ind+1]
      if '-fr' in args:
          ind = args.index("-fr")
          rem_file = args[ind+1]
      if '-fmt' in sys.argv:
          ind = sys.argv.index("-fmt")
          fmt = sys.argv[ind+1]
      if '-sav' in sys.argv:
          plots = 1
          verbose = 0
      else:
          plots = 0
      if '-n' in sys.argv:
          label = 1
      else:
          label = 0
      hyst_file = os.path.realpath(os.path.join(dir_path, hyst_file))
      rem_file = os.path.realpath(os.path.join(dir_path, rem_file))
      #
      # initialize some variables
      # define figure numbers for Day,S-Bc,S-Bcr
      DSC = {}
      DSC['day'], DSC['S-Bc'], DSC['S-Bcr'], DSC['bcr1-bcr2'] = 1, 2, 3, 4
      pmagplotlib.plot_init(DSC['day'], 5, 5)
      pmagplotlib.plot_init(DSC['S-Bc'], 5, 5)
      pmagplotlib.plot_init(DSC['S-Bcr'], 5, 5)
      pmagplotlib.plot_init(DSC['bcr1-bcr2'], 5, 5)
      #
      #
      hyst_data, file_type = pmag.magic_read(hyst_file)
      rem_data, file_type = pmag.magic_read(rem_file)
      #
      S, BcrBc, Bcr2, Bc, hsids, Bcr = [], [], [], [], [], []
      Ms, Bcr1, Bcr1Bc, S1 = [], [], [], []
      names = []
      locations = ''
      for rec in hyst_data:
          if 'er_location_name' in rec.keys() and rec['er_location_name'] not in locations:
              locations = locations+rec['er_location_name']+'_'
          if rec['hysteresis_bcr'] != "" and rec['hysteresis_mr_moment'] != "":
              S.append(float(rec['hysteresis_mr_moment']) /
                       float(rec['hysteresis_ms_moment']))
              Bcr.append(float(rec['hysteresis_bcr']))
              Bc.append(float(rec['hysteresis_bc']))
              BcrBc.append(Bcr[-1]/Bc[-1])
              if 'er_synthetic_name' in rec.keys() and rec['er_synthetic_name'] != "":
                  rec['er_specimen_name'] = rec['er_synthetic_name']
              hsids.append(rec['er_specimen_name'])
              names.append(rec['er_specimen_name'])
      if len(rem_data) > 0:
          for rec in rem_data:
              if rec['remanence_bcr'] != "" and float(rec['remanence_bcr']) > 0:
                  try:
                      ind = hsids.index(rec['er_specimen_name'])
                      Bcr1.append(float(rec['remanence_bcr']))
                      Bcr1Bc.append(Bcr1[-1]/Bc[ind])
                      S1.append(S[ind])
                      Bcr2.append(Bcr[ind])
                  except ValueError:
                      if verbose:
                          print('hysteresis data for ',
                                rec['er_specimen_name'], ' not found')
      #
      # now plot the day and S-Bc, S-Bcr plots
      #
      leglist = []
      if label == 0:
          names = []
      if len(Bcr1) > 0:
          pmagplotlib.plot_day(DSC['day'], Bcr1Bc, S1, 'ro', names=names)
          pmagplotlib.plot_s_bcr(DSC['S-Bcr'], Bcr1, S1, 'ro')
          pmagplotlib.plot_init(DSC['bcr1-bcr2'], 5, 5)
          pmagplotlib.plot_bcr(DSC['bcr1-bcr2'], Bcr1, Bcr2)
      else:
          del DSC['bcr1-bcr2']
      pmagplotlib.plot_day(DSC['day'], BcrBc, S, 'bs', names=names)
      pmagplotlib.plot_s_bcr(DSC['S-Bcr'], Bcr, S, 'bs')
      pmagplotlib.plot_s_bc(DSC['S-Bc'], Bc, S, 'bs')
      files = {}
      if len(locations) > 0:
          locations = locations[:-1]
      for key in DSC.keys():
          if pmagplotlib.isServer:  # use server plot naming convention
              files[key] = 'LO:_'+locations+'_' + \
                  'SI:__SA:__SP:__TY:_'+key+'_.'+fmt
          else:  # use more readable plot naming convention
              files[key] = '{}_{}.{}'.format(locations, key, fmt)
      if verbose:
          pmagplotlib.draw_figs(DSC)
          ans = raw_input(" S[a]ve to save plots, return to quit:  ")
          if ans == "a":
              pmagplotlib.save_plots(DSC, files)
          else:
              sys.exit()
      if plots:
          pmagplotlib.save_plots(DSC, files)