summaryrefslogtreecommitdiffstats
path: root/Doc/library/math.rst
diff options
context:
space:
mode:
authorGeorg Brandl <georg@python.org>2007-08-15 14:28:22 (GMT)
committerGeorg Brandl <georg@python.org>2007-08-15 14:28:22 (GMT)
commit116aa62bf54a39697e25f21d6cf6799f7faa1349 (patch)
tree8db5729518ed4ca88e26f1e26cc8695151ca3eb3 /Doc/library/math.rst
parent739c01d47b9118d04e5722333f0e6b4d0c8bdd9e (diff)
downloadcpython-116aa62bf54a39697e25f21d6cf6799f7faa1349.zip
cpython-116aa62bf54a39697e25f21d6cf6799f7faa1349.tar.gz
cpython-116aa62bf54a39697e25f21d6cf6799f7faa1349.tar.bz2
Move the 3k reST doc tree in place.
Diffstat (limited to 'Doc/library/math.rst')
-rw-r--r--Doc/library/math.rst227
1 files changed, 227 insertions, 0 deletions
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
new file mode 100644
index 0000000..17c75d3
--- /dev/null
+++ b/Doc/library/math.rst
@@ -0,0 +1,227 @@
+
+:mod:`math` --- Mathematical functions
+======================================
+
+.. module:: math
+ :synopsis: Mathematical functions (sin() etc.).
+
+
+This module is always available. It provides access to the mathematical
+functions defined by the C standard.
+
+These functions cannot be used with complex numbers; use the functions of the
+same name from the :mod:`cmath` module if you require support for complex
+numbers. The distinction between functions which support complex numbers and
+those which don't is made since most users do not want to learn quite as much
+mathematics as required to understand complex numbers. Receiving an exception
+instead of a complex result allows earlier detection of the unexpected complex
+number used as a parameter, so that the programmer can determine how and why it
+was generated in the first place.
+
+The following functions are provided by this module. Except when explicitly
+noted otherwise, all return values are floats.
+
+Number-theoretic and representation functions:
+
+
+.. function:: ceil(x)
+
+ Return the ceiling of *x* as a float, the smallest integer value greater than or
+ equal to *x*.
+
+
+.. function:: fabs(x)
+
+ Return the absolute value of *x*.
+
+
+.. function:: floor(x)
+
+ Return the floor of *x* as a float, the largest integer value less than or equal
+ to *x*.
+
+
+.. function:: fmod(x, y)
+
+ Return ``fmod(x, y)``, as defined by the platform C library. Note that the
+ Python expression ``x % y`` may not return the same result. The intent of the C
+ standard is that ``fmod(x, y)`` be exactly (mathematically; to infinite
+ precision) equal to ``x - n*y`` for some integer *n* such that the result has
+ the same sign as *x* and magnitude less than ``abs(y)``. Python's ``x % y``
+ returns a result with the sign of *y* instead, and may not be exactly computable
+ for float arguments. For example, ``fmod(-1e-100, 1e100)`` is ``-1e-100``, but
+ the result of Python's ``-1e-100 % 1e100`` is ``1e100-1e-100``, which cannot be
+ represented exactly as a float, and rounds to the surprising ``1e100``. For
+ this reason, function :func:`fmod` is generally preferred when working with
+ floats, while Python's ``x % y`` is preferred when working with integers.
+
+
+.. function:: frexp(x)
+
+ Return the mantissa and exponent of *x* as the pair ``(m, e)``. *m* is a float
+ and *e* is an integer such that ``x == m * 2**e`` exactly. If *x* is zero,
+ returns ``(0.0, 0)``, otherwise ``0.5 <= abs(m) < 1``. This is used to "pick
+ apart" the internal representation of a float in a portable way.
+
+
+.. function:: ldexp(x, i)
+
+ Return ``x * (2**i)``. This is essentially the inverse of function
+ :func:`frexp`.
+
+
+.. function:: modf(x)
+
+ Return the fractional and integer parts of *x*. Both results carry the sign of
+ *x*, and both are floats.
+
+Note that :func:`frexp` and :func:`modf` have a different call/return pattern
+than their C equivalents: they take a single argument and return a pair of
+values, rather than returning their second return value through an 'output
+parameter' (there is no such thing in Python).
+
+For the :func:`ceil`, :func:`floor`, and :func:`modf` functions, note that *all*
+floating-point numbers of sufficiently large magnitude are exact integers.
+Python floats typically carry no more than 53 bits of precision (the same as the
+platform C double type), in which case any float *x* with ``abs(x) >= 2**52``
+necessarily has no fractional bits.
+
+Power and logarithmic functions:
+
+
+.. function:: exp(x)
+
+ Return ``e**x``.
+
+
+.. function:: log(x[, base])
+
+ Return the logarithm of *x* to the given *base*. If the *base* is not specified,
+ return the natural logarithm of *x* (that is, the logarithm to base *e*).
+
+ .. versionchanged:: 2.3
+ *base* argument added.
+
+
+.. function:: log10(x)
+
+ Return the base-10 logarithm of *x*.
+
+
+.. function:: pow(x, y)
+
+ Return ``x**y``.
+
+
+.. function:: sqrt(x)
+
+ Return the square root of *x*.
+
+Trigonometric functions:
+
+
+.. function:: acos(x)
+
+ Return the arc cosine of *x*, in radians.
+
+
+.. function:: asin(x)
+
+ Return the arc sine of *x*, in radians.
+
+
+.. function:: atan(x)
+
+ Return the arc tangent of *x*, in radians.
+
+
+.. function:: atan2(y, x)
+
+ Return ``atan(y / x)``, in radians. The result is between ``-pi`` and ``pi``.
+ The vector in the plane from the origin to point ``(x, y)`` makes this angle
+ with the positive X axis. The point of :func:`atan2` is that the signs of both
+ inputs are known to it, so it can compute the correct quadrant for the angle.
+ For example, ``atan(1``) and ``atan2(1, 1)`` are both ``pi/4``, but ``atan2(-1,
+ -1)`` is ``-3*pi/4``.
+
+
+.. function:: cos(x)
+
+ Return the cosine of *x* radians.
+
+
+.. function:: hypot(x, y)
+
+ Return the Euclidean norm, ``sqrt(x*x + y*y)``. This is the length of the vector
+ from the origin to point ``(x, y)``.
+
+
+.. function:: sin(x)
+
+ Return the sine of *x* radians.
+
+
+.. function:: tan(x)
+
+ Return the tangent of *x* radians.
+
+Angular conversion:
+
+
+.. function:: degrees(x)
+
+ Converts angle *x* from radians to degrees.
+
+
+.. function:: radians(x)
+
+ Converts angle *x* from degrees to radians.
+
+Hyperbolic functions:
+
+
+.. function:: cosh(x)
+
+ Return the hyperbolic cosine of *x*.
+
+
+.. function:: sinh(x)
+
+ Return the hyperbolic sine of *x*.
+
+
+.. function:: tanh(x)
+
+ Return the hyperbolic tangent of *x*.
+
+The module also defines two mathematical constants:
+
+
+.. data:: pi
+
+ The mathematical constant *pi*.
+
+
+.. data:: e
+
+ The mathematical constant *e*.
+
+.. note::
+
+ The :mod:`math` module consists mostly of thin wrappers around the platform C
+ math library functions. Behavior in exceptional cases is loosely specified
+ by the C standards, and Python inherits much of its math-function
+ error-reporting behavior from the platform C implementation. As a result,
+ the specific exceptions raised in error cases (and even whether some
+ arguments are considered to be exceptional at all) are not defined in any
+ useful cross-platform or cross-release way. For example, whether
+ ``math.log(0)`` returns ``-Inf`` or raises :exc:`ValueError` or
+ :exc:`OverflowError` isn't defined, and in cases where ``math.log(0)`` raises
+ :exc:`OverflowError`, ``math.log(0L)`` may raise :exc:`ValueError` instead.
+
+
+.. seealso::
+
+ Module :mod:`cmath`
+ Complex number versions of many of these functions.
+