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serhiy-storchaka merged 2 commits into from
May 4, 2017
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bpo-29956: Improve the math.exp() related documentation. #1073

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bpo-29956: Improve the math.exp() related documentation.
serhiy-storchaka Apr 10, 2017
f1f1a8d
Remove the ambiguity.
serhiy-storchaka May 4, 2017
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11 changes: 8 additions & 3 deletions Doc/library/cmath.rst
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Expand Up @@ -47,7 +47,7 @@ rectangular coordinates to polar coordinates and back.

Return the phase of *x* (also known as the *argument* of *x*), as a
float. ``phase(x)`` is equivalent to ``math.atan2(x.imag,
x.real)``. The result lies in the range [-π, π], and the branch
x.real)``. The result lies in the range [-\ *π*, *π*], and the branch
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@mdickinson mdickinson May 4, 2017

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Strictly speaking, these should probably be 𝜋 (U+1D70B) rather than *π*, and similarly 𝑒 (U+1D452) rather than *e*. But those characters are outside the BMP, and I'm not sure what browser support is like.

cut for this operation lies along the negative real axis,
continuous from above. On systems with support for signed zeros
(which includes most systems in current use), this means that the
Expand Down Expand Up @@ -86,7 +86,8 @@ Power and logarithmic functions

.. function:: exp(x)

Return the exponential value ``e**x``.
Return *e* raised to the power *x*, where *e* is the base of natural
logarithms.


.. function:: log(x[, base])
Expand Down Expand Up @@ -243,7 +244,6 @@ Classification functions
Constants
---------


.. data:: pi

The mathematical constant *π*, as a float.
Expand All @@ -253,32 +253,37 @@ Constants

The mathematical constant *e*, as a float.


.. data:: tau

The mathematical constant *τ*, as a float.

.. versionadded:: 3.6


.. data:: inf

Floating-point positive infinity. Equivalent to ``float('inf')``.

.. versionadded:: 3.6


.. data:: infj

Complex number with zero real part and positive infinity imaginary
part. Equivalent to ``complex(0.0, float('inf'))``.

.. versionadded:: 3.6


.. data:: nan

A floating-point "not a number" (NaN) value. Equivalent to
``float('nan')``.

.. versionadded:: 3.6


.. data:: nanj

Complex number with zero real part and NaN imaginary part. Equivalent to
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27 changes: 18 additions & 9 deletions Doc/library/math.rst
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Expand Up @@ -42,15 +42,18 @@ Number-theoretic and representation functions
*y*. On platforms that support signed zeros, ``copysign(1.0, -0.0)``
returns *-1.0*.


.. function:: fabs(x)

Return the absolute value of *x*.


.. function:: factorial(x)

Return *x* factorial. Raises :exc:`ValueError` if *x* is not integral or
is negative.


.. function:: floor(x)

Return the floor of *x*, the largest integer less than or equal to *x*.
Expand Down Expand Up @@ -220,12 +223,15 @@ Power and logarithmic functions

.. function:: exp(x)

Return e raised to the power *x*, where e = 2.718281... is the base
of natural logarithms.
Return *e* raised to the power *x*, where *e* = 2.718281... is the base
of natural logarithms. This is usually more accurate than ``math.e ** x``
or ``pow(math.e, x)``.


.. function:: expm1(x)

Return ``e**x - 1``. For small floats *x*, the subtraction in ``exp(x) - 1``
Return *e* raised to the power *x*, minus 1. Here *e* is the base of natural
logarithms. For small floats *x*, the subtraction in ``exp(x) - 1``
can result in a `significant loss of precision
<https://en.wikipedia.org/wiki/Loss_of_significance>`_\; the :func:`expm1`
function provides a way to compute this quantity to full precision::
Expand Down Expand Up @@ -290,10 +296,10 @@ Power and logarithmic functions

Return the square root of *x*.


Trigonometric functions
-----------------------


.. function:: acos(x)

Return the arc cosine of *x*, in radians.
Expand Down Expand Up @@ -339,10 +345,10 @@ Trigonometric functions

Return the tangent of *x* radians.


Angular conversion
------------------


.. function:: degrees(x)

Convert angle *x* from radians to degrees.
Expand All @@ -352,6 +358,7 @@ Angular conversion

Convert angle *x* from degrees to radians.


Hyperbolic functions
--------------------

Expand Down Expand Up @@ -440,23 +447,25 @@ Constants

.. data:: pi

The mathematical constant π = 3.141592..., to available precision.
The mathematical constant *π* = 3.141592..., to available precision.


.. data:: e

The mathematical constant e = 2.718281..., to available precision.
The mathematical constant *e* = 2.718281..., to available precision.


.. data:: tau

The mathematical constant τ = 6.283185..., to available precision.
Tau is a circle constant equal to 2π, the ratio of a circle's circumference to
The mathematical constant *τ* = 6.283185..., to available precision.
Tau is a circle constant equal to 2\ *π*, the ratio of a circle's circumference to
its radius. To learn more about Tau, check out Vi Hart's video `Pi is (still)
Wrong <https://www.youtube.com/watch?v=jG7vhMMXagQ>`_, and start celebrating
`Tau day <http://tauday.com/>`_ by eating twice as much pie!

.. versionadded:: 3.6


.. data:: inf

A floating-point positive infinity. (For negative infinity, use
Expand Down
4 changes: 2 additions & 2 deletions Doc/whatsnew/3.6.rst
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Expand Up @@ -908,7 +908,7 @@ return value.
cmath
-----

The new :const:`cmath.tau` (τ) constant has been added.
The new :const:`cmath.tau` (*τ*) constant has been added.
(Contributed by Lisa Roach in :issue:`12345`, see :pep:`628` for details.)

New constants: :const:`cmath.inf` and :const:`cmath.nan` to
Expand Down Expand Up @@ -1199,7 +1199,7 @@ be reopened.
math
----

The tau (τ) constant has been added to the :mod:`math` and :mod:`cmath`
The tau (*τ*) constant has been added to the :mod:`math` and :mod:`cmath`
modules.
(Contributed by Lisa Roach in :issue:`12345`, see :pep:`628` for details.)

Expand Down