def num2tamilstr_american( *args ):
    number = args[0]
    """ work till 1000 trillion  - 1 - i.e  = 1e12*1e3 - 1.
        turn number into a numeral, American style. Fractions upto 1e-30. """

    if not any( filter( lambda T: isinstance( number, T), [int, str, unicode, long, float]) ) or isinstance(number,complex):
        raise Exception('num2tamilstr_american input has to be long or integer')
    if float(number) >= long(1e15):
        raise Exception('num2tamilstr input is too large')
    if float(number) < 0:
        return u"- "+num2tamilstr_american( -float(number) )

    units = (u'பூஜ்ஜியம்', u'ஒன்று', u'இரண்டு', u'மூன்று', u'நான்கு', u'ஐந்து', u'ஆறு', u'ஏழு', u'எட்டு', u'ஒன்பது', u'பத்து') # 0-10
    hundreds = ( u'நூறு', u'இருநூறு', u'முன்னூறு', u'நாநூறு',u'ஐநூறு', u'அறுநூறு', u'எழுநூறு', u'எண்ணூறு', u'தொள்ளாயிரம்') #100 - 900

    one_thousand_prefix = u'ஓர்'
    thousands = (u'ஆயிரம்',u'ஆயிரத்து')

    one_prefix = u'ஒரு'
    mil = u'மில்லியன்'
    million = (mil,mil)

    bil = u'பில்லியன்'
    billion = (bil,bil)

    tril = u'டிரில்லியன்'
    trillion = (tril,tril)

    n_one = 1
    n_ten = 10
    n_hundred = 100
    n_thousand = 1000
    n_million = 1000*n_thousand
    n_billion = long(1000*n_million)
    n_trillion = long(1000*n_billion)

    suffix_base = { n_trillion: trillion,
                    n_billion : billion,
                    n_million : million,
                    n_thousand : thousands}

    num_map = {n_trillion : [one_prefix,trillion[0]],
               n_billion : [one_prefix,billion[0]],
               n_million  : [one_prefix,million[0]],
               n_thousand : [one_thousand_prefix, thousands[0]],
               n_hundred : [hundreds[0]], #special
               n_ten : [units[10]],
               n_one : [units[1]]}

    all_bases = [n_trillion,n_billion, n_million, n_thousand, n_hundred, n_ten,n_one]
    allowed_bases = list(filter( lambda base: float(number) >= base, all_bases ))

    # handle fractional parts
    if float(number) > 0.0 and float(number) <= 1000.0:
        return num2tamilstr(number)

    if isinstance(number,str) or isinstance(number,unicode):
        result = u""
        number = number.strip()
        assert(len(args) == 1)
        assert(len(number) > 0)
        is_negative = number[0] == "-"
        if  is_negative:
            number = number[1:]
        frac_part = u""
        if number.find(".") >= 0:
            rat_part,frac_part = number.split(".")
            frac_part = num2tamilstr_american(u"0."+frac_part)
        else:
            rat_part = number
        if len(rat_part) > 0:
            result = num2tamilstr_american(float(rat_part))
        result = result +u" "+ frac_part
        return result.strip()

    if len(allowed_bases) >= 1:
        n_base = allowed_bases[0]
        if number == n_base:
            return u" ".join(num_map[n_base])
        quotient_number = long( number/n_base )
        residue_number = number - n_base*quotient_number

        if n_base < n_thousand:
            raise Exception("This can never happen")
        else:
            if ( quotient_number == 1 ):
                if n_base == n_thousand:
                    numeral = one_thousand_prefix+u' '
                else:
                    numeral = one_prefix+u' '
            else:
                numeral = num2tamilstr( quotient_number )
        if n_base >= n_thousand:
            suffix = suffix_base[n_base][long(residue_number >= 1)]
            if residue_number == 0:
                return numeral + u' ' + suffix
            numeral = numeral + u' ' + suffix
        residue_numeral = num2tamilstr_american( residue_number )
        return numeral+u' '+residue_numeral

    # number has to be zero
    return units[0]