Chapter 5: Numbers & Bits (Appendix)¶

The `Decimal` Type¶

In [1]:

from decimal import Decimal, getcontext

In [2]:

getcontext()

Out[2]:

Context(prec=28, rounding=ROUND_HALF_EVEN, Emin=-999999, Emax=999999, capitals=1, clamp=0, flags=[], traps=[InvalidOperation, DivisionByZero, Overflow])

In [3]:

Decimal(42)

Out[3]:

Decimal('42')

In [4]:

Decimal("0.1")

Out[4]:

Decimal('0.1')

In [5]:

Decimal("1e-3")

Out[5]:

Decimal('0.001')

In [6]:

Decimal(0.1)  # do not do this!

Out[6]:

Decimal('0.1000000000000000055511151231257827021181583404541015625')

In [7]:

Decimal("0.1") + Decimal("0.2")

Out[7]:

Decimal('0.3')

In [8]:

Decimal("0.1") + Decimal("0.2") == Decimal("0.3")

Out[8]:

True

In [9]:

Decimal("0.10000") + Decimal("0.20000")

Out[9]:

Decimal('0.30000')

In [11]:

21 + Decimal(21)

Out[11]:

Decimal('42')

In [13]:

Decimal(1) / 10

Out[13]:

Decimal('0.1')

In [16]:

1.0 * Decimal(42)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[16], line 1
----> 1 1.0 * Decimal(42)

TypeError: unsupported operand type(s) for *: 'float' and 'decimal.Decimal'

In [18]:

Decimal(2).sqrt()

Out[18]:

Decimal('1.414213562373095048801688724')

In [19]:

two = Decimal(2).sqrt() ** 2

two

Out[19]:

Decimal('1.999999999999999999999999999')

In [20]:

two.quantize(Decimal("0.0000"))

Out[20]:

Decimal('2.0000')

The `Fraction` Type¶

In [32]:

from fractions import Fraction

In [33]:

Fraction(1, 3)  # 1 / 3 with "full" precision

Out[33]:

Fraction(1, 3)

In [34]:

Fraction("1/3")  # 1 / 3 with "full" precision

Out[34]:

Fraction(1, 3)

In [35]:

Fraction("0.3333333333")  # 1 / 3 with a precision of 10 significant digits

Out[35]:

Fraction(3333333333, 10000000000)

In [39]:

Fraction(Decimal("0.1"))

Out[39]:

Fraction(1, 10)

In [40]:

Fraction(0.1)

Out[40]:

Fraction(3602879701896397, 36028797018963968)

In [41]:

Fraction(3, 2) + Fraction(1, 4)

Out[41]:

Fraction(7, 4)

In [42]:

Fraction(5, 2) - 2

Out[42]:

Fraction(1, 2)

In [43]:

3 * Fraction(1, 3)

Out[43]:

Fraction(1, 1)

In [44]:

Fraction(3, 2) * Fraction(2, 3)

Out[44]:

Fraction(1, 1)

In [45]:

10.0 * Fraction(1, 100)  # do not do this!

Out[45]:

0.1

In [46]:

format(10.0 * Fraction(1, 100), ".50f")

Out[46]:

'0.10000000000000000555111512312578270211815834045410'

Chapter 5: Numbers & Bits (Appendix)¶

The Decimal Type¶

The Fraction Type¶

The `Decimal` Type¶

The `Fraction` Type¶