Feature #1534

Added PyFloat_GetMax(), PyFloat_GetMin() and PyFloat_GetInfo() to the float API.
Added a dictionary sys.float_info with information about the internal floating point type to the sys module.

2 files changed, 59 insertions, 0 deletions

diff --git a/Doc/c-api/concrete.rst b/Doc/c-api/concrete.rst
index a02332a..aad031b 100644
--- a/Doc/c-api/concrete.rst
+++ b/Doc/c-api/concrete.rst
@@ -557,6 +557,23 @@ Floating Point Objects
    without error checking.
 
 
+.. cfunction:: PyObject* PyFloat_GetInfo(void)
+
+   Return a :ctype:`PyDictObject` object which contains information about the
+   precision, minimum and maximum values of a float. It's a thin wrapper
+   around the header file :file:`float.h`.
+
+
+.. cfunction:: double PyFloat_GetMax(void)
+
+   Return the maximum representable finite float *DBL_MAX* as C :ctype:`double`.
+
+
+.. cfunction:: double PyFloat_GetMin(void)
+
+   Return the minimum normalized positive float *DBL_MIN* as C :ctype:`double`.
+
+
 .. _complexobjects:
 
 Complex Number Objects
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index f254003..d33f532 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -240,6 +240,48 @@ always available.
       Use :mod:`atexit` instead.
 
 
+.. data:: float_info
+
+   A dict holding information about the float type. It contains low level
+   information about the precision and internal representation. Please study
+   your system's :file:`float.h` for more information.
+
+   +---------------------+--------------------------------------------------+
+   | key                 |  explanation                                     |
+   +=====================+==================================================+
+   | :const:`epsilon`    | Difference between 1 and the next representable  |
+   |                     | floating point number                            |
+   +---------------------+--------------------------------------------------+
+   | :const:`dig`        | digits (see :file:`float.h`)                     |
+   +---------------------+--------------------------------------------------+
+   | :const:`mant_dig`   | mantissa digits (see :file:`float.h`)            |
+   +---------------------+--------------------------------------------------+
+   | :const:`max`        | maximum representable finite float               |
+   +---------------------+--------------------------------------------------+
+   | :const:`max_exp`    | maximum int e such that radix**(e-1) is in the   |
+   |                     | range of finite representable floats             |
+   +---------------------+--------------------------------------------------+
+   | :const:`max_10_exp` | maximum int e such that 10**e is in the          |
+   |                     | range of finite representable floats             |
+   +---------------------+--------------------------------------------------+
+   | :const:`min`        | Minimum positive normalizer float                |
+   +---------------------+--------------------------------------------------+
+   | :const:`min_exp`    | minimum int e such that radix**(e-1) is a        |
+   |                     | normalized float                                 |
+   +---------------------+--------------------------------------------------+
+   | :const:`min_10_exp` | minimum int e such that 10**e is a normalized    |
+   |                     | float                                            |
+   +---------------------+--------------------------------------------------+
+   | :const:`radix`      | radix of exponent                                |
+   +---------------------+--------------------------------------------------+
+   | :const:`rounds`     | addition rounds (see :file:`float.h`)            |
+   +---------------------+--------------------------------------------------+
+
+   .. note::
+
+      The information in the table is simplified.
+
+
 .. function:: getcheckinterval()
 
    Return the interpreter's "check interval"; see :func:`setcheckinterval`.