Esempio n. 1
0
 def _make_PrecisionReal(self, value, prec):
     if value[0] == 'Rational':
         assert len(value) == 3
         x = sympy.Rational(*value[1:])
     elif value[0] == 'DecimalString':
         assert len(value) == 2
         x = value[1]
     else:
         assert False
     return ma.PrecisionReal(sympy.Float(x, prec))
Esempio n. 2
0
    def convert_Number(self, node):
        s = node.value
        if s[0] == '-':
            sign_prefix, s = s[0], s[1:]
            sign = -1
        else:
            sign_prefix = ''
            sign = 1

        # fast exit
        if s.isdigit():
            return ma.Integer(sign * int(s))

        # Look for base
        s = s.split('^^')
        if len(s) == 1:
            base, s = 10, s[0]
        else:
            assert len(s) == 2
            base, s = int(s[0]), s[1]
            assert 2 <= base <= 36

        # Look for mantissa
        s = s.split('*^')
        if len(s) == 1:
            n, s = 0, s[0]
        else:
            # TODO: modify regex and provide error message if n not an int
            n, s = int(s[1]), s[0]

        # Look at precision ` suffix to get precision/accuracy
        prec, acc = None, None
        s = s.split('`', 1)
        if len(s) == 1:
            s, suffix = s[0], None
        else:
            s, suffix = s[0], s[1]

        # Look for decimal point
        if '.' not in s:
            if suffix is None:
                if n < 0:
                    return ma.Rational(sign * int(s, base), base**abs(n))
                else:
                    return ma.Integer(sign * int(s, base) * (base**n))
            else:
                s = s + '.'

        if base == 10:
            man = s
            if n != 0:
                s = s + 'E' + str(n)

            if suffix is None:
                # MachineReal/PrecisionReal is determined by number of digits
                # in the mantissa
                d = len(man) - 2  # one less for decimal point
                if d < reconstruct_digits(machine_precision):
                    result = float(sign_prefix + s)
                else:
                    result = sympy.Float(str(sign_prefix + s), d)
            elif suffix == '':
                result = float(sign_prefix + s)
            elif suffix.startswith('`'):
                acc = float(suffix[1:])
                x = float(s)
                if x == 0:
                    prec10 = acc
                else:
                    prec10 = acc + log10(x)
                result = sympy.Float(str(sign_prefix + s), prec10)
            else:
                result = sympy.Float(str(sign_prefix + s), float(suffix))

            if isinstance(result, float):
                return ma.MachineReal(result)
            elif isinstance(result, sympy.Float):
                return ma.PrecisionReal(result)

        # Put into standard form mantissa * base ^ n
        s = s.split('.')
        if len(s) == 1:
            man = s[0]
        else:
            n -= len(s[1])
            man = s[0] + s[1]
        man = sign * int(man, base)
        if n >= 0:
            result = sympy.Integer(man * base**n)
        else:
            result = sympy.Rational(man, base**-n)

        x = float(result)

        # determine `prec10` the digits of precision in base 10
        if suffix is None:
            acc = len(s[1])
            acc10 = acc * log10(base)
            if x == 0:
                prec10 = acc10
            else:
                prec10 = acc10 + log10(abs(x))
            if prec10 < reconstruct_digits(machine_precision):
                prec10 = None
        elif suffix == '':
            prec10 = None
        elif suffix.startswith('`'):
            acc = float(suffix[1:])
            acc10 = acc * log10(base)
            if x == 0:
                prec10 = acc10
            else:
                prec10 = acc10 + log10(abs(x))
        else:
            prec = float(suffix)
            prec10 = prec * log10(base)

        if prec10 is None:
            return ma.MachineReal(x)
        else:
            result = sympy.Float(result, prec10)
            return ma.PrecisionReal(result)