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diff --git a/‎Doc/library/cmath.rst‎
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diff --git a/‎Doc/library/math.rst‎
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diff --git a/‎Include/Python.h‎
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diff --git a/‎Include/complexobject.h‎
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diff --git a/‎Include/floatobject.h‎
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@@ -14,8 +14,81 @@ method: these methods are used to convert the object to a complex or
 floating-point number, respectively, and the function is then applied to the
 result of the conversion.
 
-The functions are:
+.. note::
 
+   On platforms with hardware and system-level support for signed
+   zeros, functions involving branch cuts are continuous on *both*
+   sides of the branch cut: the sign of the zero distinguishes one
+   side of the branch cut from the other.  On platforms that do not
+   support signed zeros the continuity is as specified below.
+
+
+Complex coordinates
+-------------------
+
+Complex numbers can be expressed by two important coordinate systems.
+Python's :class:`complex` type uses rectangular coordinates where a number
+on the complex plain is defined by two floats, the real part and the imaginary
+part.
+
+Definition::
+
+   z = x + 1j * y
+
+   x := real(z)
+   y := imag(z)
+
+In engineering the polar coordinate system is popular for complex numbers. In
+polar coordinates a complex number is defined by the radius *r* and the phase
+angle *φ*. The radius *r* is the absolute value of the complex, which can be
+viewed as distance from (0, 0). The radius *r* is always 0 or a positive float.
+The phase angle *φ* is the counter clockwise angle from the positive x axis,
+e.g. *1* has the angle *0*, *1j* has the angle *π/2* and *-1* the angle *-π*.
+
+.. note::
+   While :func:`phase` and func:`polar` return *+π* for a negative real they
+   may return *-π* for a complex with a very small negative imaginary
+   part, e.g. *-1-1E-300j*.
+
+
+Definition::
+
+   z = r * exp(1j * φ)
+   z = r * cis(φ)
+
+   r := abs(z) := sqrt(real(z)**2 + imag(z)**2)
+   phi := phase(z) := atan2(imag(z), real(z))
+   cis(φ) := cos(φ) + 1j * sin(φ)
+
+
+.. function:: phase(x)
+
+   Return phase, also known as the argument, of a complex.
+
+   .. versionadded:: 2.6
+
+
+.. function:: polar(x)
+
+   Convert a :class:`complex` from rectangular coordinates to polar 
+   coordinates. The function returns a tuple with the two elements
+   *r* and *phi*. *r* is the distance from 0 and *phi* the phase 
+   angle.
+
+   .. versionadded:: 2.6
+
+
+.. function:: rect(r, phi)
+
+   Convert from polar coordinates to rectangular coordinates and return
+   a :class:`complex`.
+
+   .. versionadded:: 2.6
+
+
+
+cmath functions
+---------------
 
 .. function:: acos(x)
 
@@ -37,30 +110,35 @@ The functions are:
 
 .. function:: asinh(x)
 
-   Return the hyperbolic arc sine of *x*. There are two branch cuts, extending
-   left from ``±1j`` to ``±∞j``, both continuous from above. These branch cuts
-   should be considered a bug to be corrected in a future release. The correct
-   branch cuts should extend along the imaginary axis, one from ``1j`` up to
-   ``∞j`` and continuous from the right, and one from ``-1j`` down to ``-∞j``
-   and continuous from the left.
+   Return the hyperbolic arc sine of *x*. There are two branch cuts:
+   One extends from ``1j`` along the imaginary axis to ``∞j``,
+   continuous from the right.  The other extends from ``-1j`` along
+   the imaginary axis to ``-∞j``, continuous from the left.
+
+   .. versionchanged:: 2.6
+      branch cuts moved to match those recommended by the C99 standard
 
 
 .. function:: atan(x)
 
    Return the arc tangent of *x*. There are two branch cuts: One extends from
-   ``1j`` along the imaginary axis to ``∞j``, continuous from the left. The
+   ``1j`` along the imaginary axis to ``∞j``, continuous from the right. The
    other extends from ``-1j`` along the imaginary axis to ``-∞j``, continuous
-   from the left. (This should probably be changed so the upper cut becomes
-   continuous from the other side.)
+   from the left.
+
+   .. versionchanged:: 2.6
+      direction of continuity of upper cut reversed
 
 
 .. function:: atanh(x)
 
    Return the hyperbolic arc tangent of *x*. There are two branch cuts: One
-   extends from ``1`` along the real axis to ``∞``, continuous from above. The
+   extends from ``1`` along the real axis to ``∞``, continuous from below. The
    other extends from ``-1`` along the real axis to ``-∞``, continuous from
-   above. (This should probably be changed so the right cut becomes continuous
-   from the other side.)
+   above.
+
+   .. versionchanged:: 2.6
+      direction of continuity of right cut reversed
 
 
 .. function:: cos(x)
@@ -78,6 +156,21 @@ The functions are:
    Return the exponential value ``e**x``.
 
 
+.. function:: isinf(x)
+
+   Return *True* if the real or the imaginary part of x is positive
+   or negative infinity.
+
+   .. versionadded:: 2.6
+
+
+.. function:: isnan(x)
+
+   Return *True* if the real or imaginary part of x is not a number (NaN).
+
+   .. versionadded:: 2.6
+
+
 .. function:: log(x[, base])
 
    Returns the logarithm of *x* to the given *base*. If the *base* is not
@@ -151,3 +244,4 @@ cuts for numerical purposes, a good reference should be the following:
    nothing's sign bit.  In Iserles, A., and Powell, M. (eds.), The state of the art
    in numerical analysis. Clarendon Press (1987) pp165-211.
 
+
@@ -128,14 +128,26 @@ Power and logarithmic functions:
    return the natural logarithm of *x* (that is, the logarithm to base *e*).
 
 
+.. function:: log1p(x)
+
+   Return the natural logarithm of *1+x* (base *e*). The
+   result is calculated in a way which is accurate for *x* near zero.
+
+   .. versionadded:: 2.6
+
+
 .. function:: log10(x)
 
    Return the base-10 logarithm of *x*.
 
 
 .. function:: pow(x, y)
 
-   Return ``x**y``.
+   Return ``x**y``. ``1.0**y`` returns *1.0*, even for ``1.0**nan``. ``0**y``
+   returns *0.* for all positive *y*, *0* and *NAN*.
+
+   .. versionchanged:: 2.6
+      The outcome of ``1**nan`` and ``0**nan`` was undefined.
 
 
 .. function:: sqrt(x)
@@ -186,6 +198,13 @@ Trigonometric functions:
    Return the sine of *x* radians.
 
 
+.. function:: asinh(x)
+
+   Return the inverse hyperbolic sine of *x*, in radians.
+
+   .. versionadded:: 2.6
+
+
 .. function:: tan(x)
 
    Return the tangent of *x* radians.
@@ -210,6 +229,13 @@ Hyperbolic functions:
    Return the hyperbolic cosine of *x*.
 
 
+.. function:: acosh(x)
+
+   Return the inverse hyperbolic cosine of *x*, in radians.
+
+   .. versionadded:: 2.6
+
+
 .. function:: sinh(x)
 
    Return the hyperbolic sine of *x*.
@@ -219,6 +245,14 @@ Hyperbolic functions:
 
    Return the hyperbolic tangent of *x*.
 
+
+.. function:: atanh(x)
+
+   Return the inverse hyperbolic tangent of *x*, in radians.
+
+   .. versionadded:: 2.6
+
+
 The module also defines two mathematical constants:
 
 
@@ -231,6 +265,7 @@ The module also defines two mathematical constants:
 
    The mathematical constant *e*.
 
+
 .. note::
 
    The :mod:`math` module consists mostly of thin wrappers around the platform C
@@ -244,9 +279,17 @@ The module also defines two mathematical constants:
    :exc:`OverflowError` isn't defined, and in cases where ``math.log(0)`` raises
    :exc:`OverflowError`, ``math.log(0L)`` may raise :exc:`ValueError` instead.
 
+   All functions return a quite *NaN* if at least one of the args is *NaN*.
+   Signaling *NaN*s raise an exception. The exception type still depends on the
+   platform and libm implementation. It's usually :exc:`ValueError` for *EDOM*
+   and :exc:`OverflowError` for errno *ERANGE*.
+
+   ..versionchanged:: 2.6
+      In earlier versions of Python the outcome of an operation with NaN as
+      input depended on platform and libm implementation.
+
 
 .. seealso::
 
    Module :mod:`cmath`
       Complex number versions of many of these functions.
-
 
@@ -57,6 +57,7 @@
 #if defined(PYMALLOC_DEBUG) && !defined(WITH_PYMALLOC)
 #error "PYMALLOC_DEBUG requires WITH_PYMALLOC"
 #endif
+#include "pymath.h"
 #include "pymem.h"
 
 #include "object.h"
 
@@ -19,13 +19,15 @@ typedef struct {
 #define c_prod _Py_c_prod
 #define c_quot _Py_c_quot
 #define c_pow _Py_c_pow
+#define c_abs _Py_c_abs
 
 PyAPI_FUNC(Py_complex) c_sum(Py_complex, Py_complex);
 PyAPI_FUNC(Py_complex) c_diff(Py_complex, Py_complex);
 PyAPI_FUNC(Py_complex) c_neg(Py_complex);
 PyAPI_FUNC(Py_complex) c_prod(Py_complex, Py_complex);
 PyAPI_FUNC(Py_complex) c_quot(Py_complex, Py_complex);
 PyAPI_FUNC(Py_complex) c_pow(Py_complex, Py_complex);
+PyAPI_FUNC(double) c_abs(Py_complex);
 
 
 /* Complex object interface */
 
@@ -21,6 +21,17 @@ PyAPI_DATA(PyTypeObject) PyFloat_Type;
 #define PyFloat_Check(op) PyObject_TypeCheck(op, &PyFloat_Type)
 #define PyFloat_CheckExact(op) (Py_TYPE(op) == &PyFloat_Type)
 
+#ifdef Py_NAN
+#define Py_RETURN_NAN return PyFloat_FromDouble(Py_NAN)
+#endif
+
+#define Py_RETURN_INF(sign) do					\
+	if (copysign(1., sign) == 1.) {				\
+		return PyFloat_FromDouble(Py_HUGE_VAL);	\
+	} else {						\
+		return PyFloat_FromDouble(-Py_HUGE_VAL);	\
+	} while(0)
+
 PyAPI_FUNC(double) PyFloat_GetMax(void);
 PyAPI_FUNC(double) PyFloat_GetMin(void);
 PyAPI_FUNC(PyObject *) PyFloat_GetInfo(void);