Python sys.float_info.mant_dig() Examples

The following are 4 code examples of sys.float_info.mant_dig(). You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. You may also want to check out all available functions/classes of the module sys.float_info , or try the search function .
Example #1
Source File: _fsum.py    From CTFCrackTools-V2 with GNU General Public License v3.0 5 votes vote down vote up 
def fsum(iterable):
    """Full precision summation.  Compute sum(iterable) without any
    intermediate accumulation of error.  Based on the 'lsum' function
    at http://code.activestate.com/recipes/393090/

    """
    tmant, texp = 0, 0
    for x in iterable:
        mant, exp = math.frexp(x)
        mant, exp = int(math.ldexp(mant, mant_dig)), exp - mant_dig
        if texp > exp:
            tmant <<= texp-exp
            texp = exp
        else:
            mant <<= exp-texp
        tmant += mant

    # Round tmant * 2**texp to a float.  The original recipe
    # used float(str(tmant)) * 2.0**texp for this, but that's
    # a little unsafe because str -> float conversion can't be
    # relied upon to do correct rounding on all platforms.
    tail = max(len(bin(abs(tmant)))-2 - mant_dig, etiny - texp)
    if tail > 0:
        h = 1 << (tail-1)
        tmant = tmant // (2*h) + bool(tmant & h and tmant & 3*h-1)
        texp += tail
    return math.ldexp(tmant, texp)
Example #2
Source File: _fsum.py    From CTFCrackTools-V2 with GNU General Public License v3.0 5 votes vote down vote up 
def fsum(iterable):
    """Full precision summation.  Compute sum(iterable) without any
    intermediate accumulation of error.  Based on the 'lsum' function
    at http://code.activestate.com/recipes/393090/

    """
    tmant, texp = 0, 0
    for x in iterable:
        mant, exp = math.frexp(x)
        mant, exp = int(math.ldexp(mant, mant_dig)), exp - mant_dig
        if texp > exp:
            tmant <<= texp-exp
            texp = exp
        else:
            mant <<= exp-texp
        tmant += mant

    # Round tmant * 2**texp to a float.  The original recipe
    # used float(str(tmant)) * 2.0**texp for this, but that's
    # a little unsafe because str -> float conversion can't be
    # relied upon to do correct rounding on all platforms.
    tail = max(len(bin(abs(tmant)))-2 - mant_dig, etiny - texp)
    if tail > 0:
        h = 1 << (tail-1)
        tmant = tmant // (2*h) + bool(tmant & h and tmant & 3*h-1)
        texp += tail
    return math.ldexp(tmant, texp)
Example #3
Source File: _fsum.py    From CTFCrackTools with GNU General Public License v3.0 5 votes vote down vote up 
def fsum(iterable):
    """Full precision summation.  Compute sum(iterable) without any
    intermediate accumulation of error.  Based on the 'lsum' function
    at http://code.activestate.com/recipes/393090/

    """
    tmant, texp = 0, 0
    for x in iterable:
        mant, exp = math.frexp(x)
        mant, exp = int(math.ldexp(mant, mant_dig)), exp - mant_dig
        if texp > exp:
            tmant <<= texp-exp
            texp = exp
        else:
            mant <<= exp-texp
        tmant += mant

    # Round tmant * 2**texp to a float.  The original recipe
    # used float(str(tmant)) * 2.0**texp for this, but that's
    # a little unsafe because str -> float conversion can't be
    # relied upon to do correct rounding on all platforms.
    tail = max(len(bin(abs(tmant)))-2 - mant_dig, etiny - texp)
    if tail > 0:
        h = 1 << (tail-1)
        tmant = tmant // (2*h) + bool(tmant & h and tmant & 3*h-1)
        texp += tail
    return math.ldexp(tmant, texp)
Example #4
Source File: _fsum.py    From CTFCrackTools with GNU General Public License v3.0 5 votes vote down vote up 
def fsum(iterable):
    """Full precision summation.  Compute sum(iterable) without any
    intermediate accumulation of error.  Based on the 'lsum' function
    at http://code.activestate.com/recipes/393090/

    """
    tmant, texp = 0, 0
    for x in iterable:
        mant, exp = math.frexp(x)
        mant, exp = int(math.ldexp(mant, mant_dig)), exp - mant_dig
        if texp > exp:
            tmant <<= texp-exp
            texp = exp
        else:
            mant <<= exp-texp
        tmant += mant

    # Round tmant * 2**texp to a float.  The original recipe
    # used float(str(tmant)) * 2.0**texp for this, but that's
    # a little unsafe because str -> float conversion can't be
    # relied upon to do correct rounding on all platforms.
    tail = max(len(bin(abs(tmant)))-2 - mant_dig, etiny - texp)
    if tail > 0:
        h = 1 << (tail-1)
        tmant = tmant // (2*h) + bool(tmant & h and tmant & 3*h-1)
        texp += tail
    return math.ldexp(tmant, texp)