DOC: Add a brief explanation of float printing

Also link to the overflow docs here.

2 files changed, 26 insertions, 0 deletions

diff --git a/doc/source/reference/arrays.scalars.rst b/doc/source/reference/arrays.scalars.rst
index 29438f70f..c3fb1f91b 100644
--- a/doc/source/reference/arrays.scalars.rst
+++ b/doc/source/reference/arrays.scalars.rst
@@ -108,6 +108,11 @@ Integer types
    :members: __init__
    :exclude-members: __init__
 
+.. note::
+
+   The numpy integer types mirror the behavior of C integers, and can therefore
+   be subject to :ref:`overflow-errors`.
+
 Signed integer types
 ++++++++++++++++++++
 
@@ -169,6 +174,25 @@ Inexact types
    :members: __init__
    :exclude-members: __init__
 
+.. note::
+
+   The printing behavior of inexact scalars is to use as few digits as possible
+   to display the result unambiguously. This means that equal values at
+   different precisions will display differently::
+
+       >>> f16 = np.float16("0.1")
+       >>> f32 = np.float32(f16)
+       >>> f64 = np.float64(f32)
+       >>> f16 == f32 == f64
+       True
+       >>> f16, f32, f64
+       (0.1, 0.099975586, 0.0999755859375)
+
+   Note that none of these floats hold the exact value :math:`\frac{1}{10}`;
+   ``f16`` prints as ``0.1`` because it is as close to that value as possible,
+   whereas the other types do not as they have more precision and therefore have
+   closer values.
+
 Floating-point types
 ++++++++++++++++++++
 
diff --git a/doc/source/user/basics.types.rst b/doc/source/user/basics.types.rst
index ec2af409a..781dd66e5 100644
--- a/doc/source/user/basics.types.rst
+++ b/doc/source/user/basics.types.rst
@@ -261,6 +261,8 @@ identical behaviour between arrays and scalars, irrespective of whether the
 value is inside an array or not.  NumPy scalars also have many of the same
 methods arrays do.
 
+.. _overflow-errors:
+
 Overflow Errors
 ===============