Issue #29282: Backed out changeset b33012ef1417

Doc/library/math.rst

@@ -57,21 +57,6 @@ Number-theoretic and representation functions
    If *x* is not a float, delegates to ``x.__floor__()``, which should return an
    :class:`~numbers.Integral` value.
 
-.. function:: fma(x, y, z)
-
-   Fused multiply-add operation. Return ``(x * y) + z``, computed as though with
-   infinite precision and range followed by a single round to the ``float``
-   format. This operation often provides better accuracy than the direct
-   expression ``(x * y) + z``.
-
-   This function follows the specification of the fusedMultiplyAdd operation
-   described in the IEEE 754-2008 standard. The standard leaves one case
-   implementation-defined, namely the result of ``fma(0, inf, nan)``
-   and ``fma(inf, 0, nan)``. In these cases, ``math.fma`` returns a NaN,
-   and does not raise any exception.
-
-   .. versionadded:: 3.7
-
 
 .. function:: fmod(x, y)
 

Doc/whatsnew/3.7.rst

@@ -100,15 +100,6 @@ The :const:`~unittest.mock.sentinel` attributes now preserve their identity
 when they are :mod:`copied <copy>` or :mod:`pickled <pickle>`.
 (Contributed by Serhiy Storchaka in :issue:`20804`.)
 
-math module
------------
-
-A new function :func:`~math.fma` for fused multiply-add operations has been
-added. This function computes ``x * y + z`` with only a single round, and so
-avoids any intermediate loss of precision. It wraps the ``fma`` function
-provided by C99, and follows the specification of the IEEE 754-2008
-"fusedMultiplyAdd" operation for special cases.
-
 
 Optimizations
 =============

Misc/NEWS

@@ -215,9 +215,6 @@ Core and Builtins
 Library
 -------
 
-- Issue #29282: Added new math.fma function, wrapping C99's fma
-  operation.
-
 - Issue #29197: Removed deprecated function ntpath.splitunc().
 
 - Issue #29210: Removed support of deprecated argument "exclude" in

Modules/clinic/mathmodule.c.h

@@ -80,40 +80,6 @@ PyDoc_STRVAR(math_factorial__doc__,
 #define MATH_FACTORIAL_METHODDEF    \
     {"factorial", (PyCFunction)math_factorial, METH_O, math_factorial__doc__},
 
-PyDoc_STRVAR(math_fma__doc__,
-"fma($module, x, y, z, /)\n"
-"--\n"
-"\n"
-"Fused multiply-add operation. Compute (x * y) + z with a single round.");
-
-#define MATH_FMA_METHODDEF    \
-    {"fma", (PyCFunction)math_fma, METH_FASTCALL, math_fma__doc__},
-
-static PyObject *
-math_fma_impl(PyObject *module, double x, double y, double z);
-
-static PyObject *
-math_fma(PyObject *module, PyObject **args, Py_ssize_t nargs, PyObject *kwnames)
-{
-    PyObject *return_value = NULL;
-    double x;
-    double y;
-    double z;
-
-    if (!_PyArg_ParseStack(args, nargs, "ddd:fma",
-        &x, &y, &z)) {
-        goto exit;
-    }
-
-    if (!_PyArg_NoStackKeywords("fma", kwnames)) {
-        goto exit;
-    }
-    return_value = math_fma_impl(module, x, y, z);
-
-exit:
-    return return_value;
-}
-
 PyDoc_STRVAR(math_trunc__doc__,
 "trunc($module, x, /)\n"
 "--\n"
@@ -570,4 +536,4 @@ math_isclose(PyObject *module, PyObject **args, Py_ssize_t nargs, PyObject *kwna
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=f428e1075d00c334 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=71806f73a5c4bf0b input=a9049054013a1b77]*/

Modules/mathmodule.c

@@ -1595,47 +1595,6 @@ math_factorial(PyObject *module, PyObject *arg)
 }
 
 
-/*[clinic input]
-math.fma
-
-    x: double
-    y: double
-    z: double
-    /
-
-Fused multiply-add operation. Compute (x * y) + z with a single round.
-[clinic start generated code]*/
-
-static PyObject *
-math_fma_impl(PyObject *module, double x, double y, double z)
-/*[clinic end generated code: output=4fc8626dbc278d17 input=2ae8bb2a6e0f8b77]*/
-{
-    double r;
-    r = fma(x, y, z);
-
-    /* Fast path: if we got a finite result, we're done. */
-    if (Py_IS_FINITE(r)) {
-        return PyFloat_FromDouble(r);
-    }
-
-    /* Non-finite result. Raise an exception if appropriate, else return r. */
-    if (Py_IS_NAN(r)) {
-        if (!Py_IS_NAN(x) && !Py_IS_NAN(y) && !Py_IS_NAN(z)) {
-            /* NaN result from non-NaN inputs. */
-            PyErr_SetString(PyExc_ValueError, "invalid operation in fma");
-            return NULL;
-        }
-    }
-    else if (Py_IS_FINITE(x) && Py_IS_FINITE(y) && Py_IS_FINITE(z)) {
-        /* Infinite result from finite inputs. */
-        PyErr_SetString(PyExc_OverflowError, "overflow in fma");
-        return NULL;
-    }
-
-    return PyFloat_FromDouble(r);
-}
-
-
 /*[clinic input]
 math.trunc
 
@@ -2265,7 +2224,6 @@ static PyMethodDef math_methods[] = {
     {"fabs",            math_fabs,      METH_O,         math_fabs_doc},
     MATH_FACTORIAL_METHODDEF
     MATH_FLOOR_METHODDEF
-    MATH_FMA_METHODDEF
     MATH_FMOD_METHODDEF
     MATH_FREXP_METHODDEF
     MATH_FSUM_METHODDEF