Laboratoire de l'Informatique et du Parallélisme » Pobyso

sys.stderr.write("sageNumericalOperations: loading...\n")

#

def sno_abs_is_power_of_two(number):

    """

    Check if the absolute value of a number is power of 2.

    As of Sage 7.1, the built-in is_power_of_two, only works with integer and

    returns false for negative ones.

    """

    #return is_power_of_two(abs(number))

    log2number = log(abs(number))/log(2)

    return log2number.n() == long(log2number.n())

# End sno_abs_is_power_of_two(number):

#

def sno_float_to_rat_pow_of_two_denom(number):

    """

    Convert a floating-point number into a rational where the denominator

    is a power of two

    """

    ## Argument checking.

    if not number.is_real():

        return None

    #

    (sign, mantissa, exponent) = number.sign_mantissa_exponent()

    #print sign, mantissa, exponent

    precision = number.prec()

    if sign == 1:

        return mantissa / 2^(-exponent)

    else:

        return -mantissa / 2^(-exponent)

# End sno_float_to_rat_pow_of_two_denom.

sys.stderr.write("\t...sageNumericalOperations loaded.\n")