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Diffstat (limited to 'doc/source/reference/c-api.iterator.rst')
| -rw-r--r-- | doc/source/reference/c-api.iterator.rst | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/doc/source/reference/c-api.iterator.rst b/doc/source/reference/c-api.iterator.rst index b38c21390..679763067 100644 --- a/doc/source/reference/c-api.iterator.rst +++ b/doc/source/reference/c-api.iterator.rst @@ -461,6 +461,23 @@ Construction and Destruction Then, call :c:func:`NpyIter_Reset` to allocate and fill the buffers with their initial values. + .. c:var:: NPY_ITER_COPY_IF_OVERLAP + + If any write operand has overlap with any read operand, eliminate all + overlap by making temporary copies (enabling UPDATEIFCOPY for write + operands, if necessary). A pair of operands has overlap if there is + a memory address that contains data common to both arrays. + + Because exact overlap detection has exponential runtime + in the number of dimensions, the decision is made based + on heuristics, which has false positives (needless copies in unusual + cases) but has no false negatives. + + If any read/write overlap exists, this flag ensures the result of the + operation is the same as if all operands were copied. + In cases where copies would need to be made, **the result of the + computation may be undefined without this flag!** + Flags that may be passed in ``op_flags[i]``, where ``0 <= i < nop``: .. c:var:: NPY_ITER_READWRITE @@ -591,6 +608,18 @@ Construction and Destruction returns true from the corresponding element in the ARRAYMASK operand. + .. c:var:: NPY_ITER_OVERLAP_ASSUME_ELEMENTWISE + + In memory overlap checks, assume that operands with + ``NPY_ITER_OVERLAP_ASSUME_ELEMENTWISE`` enabled are accessed only + in the iterator order. + + This enables the iterator to reason about data dependency, + possibly avoiding unnecessary copies. + + This flag has effect only if ``NPY_ITER_COPY_IF_OVERLAP`` is enabled + on the iterator. + .. c:function:: NpyIter* NpyIter_AdvancedNew(npy_intp nop, PyArrayObject** op, npy_uint32 flags, NPY_ORDER order, NPY_CASTING casting, npy_uint32* op_flags, PyArray_Descr** op_dtypes, int oa_ndim, int** op_axes, npy_intp* itershape, npy_intp buffersize) Extends :c:func:`NpyIter_MultiNew` with several advanced options providing |