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| -rw-r--r-- | Doc/library/sys.rst | 92 |
1 files changed, 49 insertions, 43 deletions
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst index c465842..315e570 100644 --- a/Doc/library/sys.rst +++ b/Doc/library/sys.rst @@ -522,49 +522,55 @@ always available. .. tabularcolumns:: |l|l|L| - +---------------------+----------------+--------------------------------------------------+ - | attribute | float.h macro | explanation | - +=====================+================+==================================================+ - | :const:`epsilon` | DBL_EPSILON | difference between 1.0 and the least value | - | | | greater than 1.0 that is representable as a float| - | | | | - | | | See also :func:`math.ulp`. | - +---------------------+----------------+--------------------------------------------------+ - | :const:`dig` | DBL_DIG | maximum number of decimal digits that can be | - | | | faithfully represented in a float; see below | - +---------------------+----------------+--------------------------------------------------+ - | :const:`mant_dig` | DBL_MANT_DIG | float precision: the number of base-``radix`` | - | | | digits in the significand of a float | - +---------------------+----------------+--------------------------------------------------+ - | :const:`max` | DBL_MAX | maximum representable positive finite float | - +---------------------+----------------+--------------------------------------------------+ - | :const:`max_exp` | DBL_MAX_EXP | maximum integer *e* such that ``radix**(e-1)`` is| - | | | a representable finite float | - +---------------------+----------------+--------------------------------------------------+ - | :const:`max_10_exp` | DBL_MAX_10_EXP | maximum integer *e* such that ``10**e`` is in the| - | | | range of representable finite floats | - +---------------------+----------------+--------------------------------------------------+ - | :const:`min` | DBL_MIN | minimum representable positive *normalized* float| - | | | | - | | | Use :func:`math.ulp(0.0) <math.ulp>` to get the | - | | | smallest positive *denormalized* representable | - | | | float. | - +---------------------+----------------+--------------------------------------------------+ - | :const:`min_exp` | DBL_MIN_EXP | minimum integer *e* such that ``radix**(e-1)`` is| - | | | a normalized float | - +---------------------+----------------+--------------------------------------------------+ - | :const:`min_10_exp` | DBL_MIN_10_EXP | minimum integer *e* such that ``10**e`` is a | - | | | normalized float | - +---------------------+----------------+--------------------------------------------------+ - | :const:`radix` | FLT_RADIX | radix of exponent representation | - +---------------------+----------------+--------------------------------------------------+ - | :const:`rounds` | FLT_ROUNDS | integer constant representing the rounding mode | - | | | used for arithmetic operations. This reflects | - | | | the value of the system FLT_ROUNDS macro at | - | | | interpreter startup time. See section 5.2.4.2.2 | - | | | of the C99 standard for an explanation of the | - | | | possible values and their meanings. | - +---------------------+----------------+--------------------------------------------------+ + +---------------------+---------------------+--------------------------------------------------+ + | attribute | float.h macro | explanation | + +=====================+=====================+==================================================+ + | ``epsilon`` | ``DBL_EPSILON`` | difference between 1.0 and the least value | + | | | greater than 1.0 that is representable as a float| + | | | | + | | | See also :func:`math.ulp`. | + +---------------------+---------------------+--------------------------------------------------+ + | ``dig`` | ``DBL_DIG`` | maximum number of decimal digits that can be | + | | | faithfully represented in a float; see below | + +---------------------+---------------------+--------------------------------------------------+ + | ``mant_dig`` | ``DBL_MANT_DIG`` | float precision: the number of base-``radix`` | + | | | digits in the significand of a float | + +---------------------+---------------------+--------------------------------------------------+ + | ``max`` | ``DBL_MAX`` | maximum representable positive finite float | + +---------------------+---------------------+--------------------------------------------------+ + | ``max_exp`` | ``DBL_MAX_EXP`` | maximum integer *e* such that ``radix**(e-1)`` is| + | | | a representable finite float | + +---------------------+---------------------+--------------------------------------------------+ + | ``max_10_exp`` | ``DBL_MAX_10_EXP`` | maximum integer *e* such that ``10**e`` is in the| + | | | range of representable finite floats | + +---------------------+---------------------+--------------------------------------------------+ + | ``min`` | ``DBL_MIN`` | minimum representable positive *normalized* float| + | | | | + | | | Use :func:`math.ulp(0.0) <math.ulp>` to get the | + | | | smallest positive *denormalized* representable | + | | | float. | + +---------------------+---------------------+--------------------------------------------------+ + | ``min_exp`` | ``DBL_MIN_EXP`` | minimum integer *e* such that ``radix**(e-1)`` is| + | | | a normalized float | + +---------------------+---------------------+--------------------------------------------------+ + | ``min_10_exp`` | ``DBL_MIN_10_EXP`` | minimum integer *e* such that ``10**e`` is a | + | | | normalized float | + +---------------------+---------------------+--------------------------------------------------+ + | ``radix`` | ``FLT_RADIX`` | radix of exponent representation | + +---------------------+---------------------+--------------------------------------------------+ + | ``rounds`` | ``FLT_ROUNDS`` | integer representing the rounding mode for | + | | | floating-point arithmetic. This reflects the | + | | | value of the system ``FLT_ROUNDS`` macro at | + | | | interpreter startup time: | + | | | ``-1`` indeterminable, | + | | | ``0`` toward zero, | + | | | ``1`` to nearest, | + | | | ``2`` toward positive infinity, | + | | | ``3`` toward negative infinity | + | | | | + | | | All other values for ``FLT_ROUNDS`` characterize | + | | | implementation-defined rounding behavior. | + +---------------------+---------------------+--------------------------------------------------+ The attribute :attr:`sys.float_info.dig` needs further explanation. If ``s`` is any string representing a decimal number with at most |