#

# Copyright 2003 Free Software Foundation, Inc.

# 

# This file is part of GNU Radio

# 

# GNU Radio is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2, or (at your option)

# any later version.

# 

# GNU Radio 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 General Public License for more details.

# 

# You should have received a copy of the GNU General Public License

# along with GNU Radio; see the file COPYING.  If not, write to

# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,

# Boston, MA 02111-1307, USA.

# 

scale_factor = {}

scale_factor['E'] = 1e18

scale_factor['P'] = 1e15

scale_factor['T'] = 1e12

scale_factor['G'] = 1e9

scale_factor['M'] = 1e6

scale_factor['k'] = 1e3

scale_factor['m'] = 1e-3

scale_factor['u'] = 1e-6

scale_factor['n'] = 1e-9

scale_factor['p'] = 1e-12

scale_factor['f'] = 1e-15

scale_factor['a'] = 1e-18

def num_to_str (n):

    '''Convert a number to a string in engineering notation.  E.g., 5e-9 -> 5n'''

    m = abs(n)

    if m >= 1e9:

        return "%gG" % (n * 1e-9)

    elif m >= 1e6:

        return "%gM" % (n * 1e-6)

    elif m >= 1e3:

        return "%gk" % (n * 1e-3)

    elif m >= 1:

        return "%g" % (n)

    elif m >= 1e-3:

        return "%gm" % (n * 1e3)

    elif m >= 1e-6:

        return "%gu" % (n * 1e6)        # where's that mu when you need it (unicode?)

    elif m >= 1e-9:

        return "%gn" % (n * 1e9)

    elif m >= 1e-12:

        return "%gp" % (n * 1e12)

    elif m >= 1e-15:

        return "%gf" % (n * 1e15)

    else:

        return "%g" % (n)

def str_to_num (value):

    '''Convert a string in engineering notation to a number.  E.g., '15m' -> 15e-3'''

    try:

        scale = 1.0

        suffix = value[-1]

        if scale_factor.has_key (suffix):

            return float (value[0:-1]) * scale_factor[suffix]

        return float (value)

    except:

        raise RuntimeError (

            "Invalid engineering notation value: %r" % (value,))