FixedPoint objects support decimal arithmetic with a fixed number of digits (called the object’s precision) after the decimal point. The number of digits before the decimal point is variable & unbounded.
The precision is usersettable on a perobject basis when a FixedPoint
is constructed, and may vary across FixedPoint objects. The precision
may also be changed after construction via FixedPoint.set_precision(p).
Note that if the precision of a FixedPoint is reduced via FixedPoint.set_precision()
,
information may be lost to rounding.
Example:
>>> x = FixedPoint("5.55") # precision defaults to 2
>>> print(x)
5.55
>>> x.set_precision(1) # round to one fraction digit
>>> print(x)
5.6
>>> print(FixedPoint("5.55", 1)) # same thing setting to 1 in constructor
5.6
>>> repr(x) # returns constructor string that reproduces object exactly
"FixedPoint('5.6', 1)"
>>>
When FixedPoint
objects of different precision are combined via +  * /,
the result is computed to the larger of the inputs’ precisions, which also
becomes the precision of the resulting FixedPoint
object. Example:
>>> print FixedPoint("3.42") + FixedPoint("100.005", 3)
103.425
>>>
When a FixedPoint
is combined with other numeric types (ints, floats,
strings representing a number) via +  * /, then similarly the computation
is carried out using – and the result inherits – the FixedPoint
’s
precision. Example:
>>> print(FixedPoint(1) / 7)
0.14
>>> print(FixedPoint(1, 30) / 7)
0.142857142857142857142857142857
>>>
The string produced by str(x) (implicitly invoked by print) always contains at least one digit before the decimal point, followed by a decimal point, followed by exactly x.get_precision() digits. If x is negative, str(x)[0] == “”.
The FixedPoint
constructor can be passed an int, long, string, float,
FixedPoint
, or any object convertible to a float via float() or to an
integer via int(). Passing a precision is optional; if specified, the
precision must be a nonnegative int. There is no inherent limit on
the size of the precision, but if very very large you’ll probably run
out of memory.
Note that conversion of floats to FixedPoint
can be surprising, and
should be avoided whenever possible. Conversion from string is exact
(up to final rounding to the requested precision), so is greatly
preferred. Example:
>>> print(FixedPoint(1.1e30))
1099999999999999993725589651456.00
>>> print(FixedPoint("1.1e30"))
1100000000000000000000000000000.00
>>>
Default class constructor. 

Create a copy of the current 

Returns fractional portion as a 

Return the precision of this 

Change the precision carried by this 
FixedPoint
(object)¶FixedPoint objects support decimal arithmetic with a fixed number of digits (called the object’s precision) after the decimal point. The number of digits before the decimal point is variable & unbounded.
The precision is usersettable on a perobject basis when a FixedPoint
is constructed, and may vary across FixedPoint objects. The precision
may also be changed after construction via FixedPoint.set_precision(p).
Note that if the precision of a FixedPoint is reduced via FixedPoint.set_precision()
,
information may be lost to rounding.
Example:
>>> x = FixedPoint("5.55") # precision defaults to 2
>>> print(x)
5.55
>>> x.set_precision(1) # round to one fraction digit
>>> print(x)
5.6
>>> print(FixedPoint("5.55", 1)) # same thing setting to 1 in constructor
5.6
>>> repr(x) # returns constructor string that reproduces object exactly
"FixedPoint('5.6', 1)"
>>>
When FixedPoint
objects of different precision are combined via +  * /,
the result is computed to the larger of the inputs’ precisions, which also
becomes the precision of the resulting FixedPoint
object. Example:
>>> print FixedPoint("3.42") + FixedPoint("100.005", 3)
103.425
>>>
When a FixedPoint
is combined with other numeric types (ints, floats,
strings representing a number) via +  * /, then similarly the computation
is carried out using – and the result inherits – the FixedPoint
’s
precision. Example:
>>> print(FixedPoint(1) / 7)
0.14
>>> print(FixedPoint(1, 30) / 7)
0.142857142857142857142857142857
>>>
The string produced by str(x) (implicitly invoked by print) always contains at least one digit before the decimal point, followed by a decimal point, followed by exactly x.get_precision() digits. If x is negative, str(x)[0] == “”.
The FixedPoint
constructor can be passed an int, long, string, float,
FixedPoint
, or any object convertible to a float via float() or to an
integer via int(). Passing a precision is optional; if specified, the
precision must be a nonnegative int. There is no inherent limit on
the size of the precision, but if very very large you’ll probably run
out of memory.
Note that conversion of floats to FixedPoint
can be surprising, and
should be avoided whenever possible. Conversion from string is exact
(up to final rounding to the requested precision), so is greatly
preferred. Example:
>>> print(FixedPoint(1.1e30))
1099999999999999993725589651456.00
>>> print(FixedPoint("1.1e30"))
1100000000000000000000000000000.00
>>>
__init__
(self, value=0, precision=DEFAULT_PRECISION)¶Default class constructor.
value – the initial value;
precision – must be an int >= 0, and defaults to DEFAULT_PRECISION
.
copy
(self)¶Create a copy of the current FixedPoint
.
frac
(self)¶Returns fractional portion as a FixedPoint
.
get_precision
(self)¶Return the precision of this FixedPoint
.
Note
The precision is the number of decimal digits carried after the decimal point, and is an int >= 0.
set_precision
(self, precision=DEFAULT_PRECISION)¶Change the precision carried by this FixedPoint
to precision.
precision – must be an int >= 0, and defaults to
DEFAULT_PRECISION
.
Note
If precision is less than this FixedPoint
’s current precision,
information may be lost to rounding.