System configuration#

When NumPy is built, information about system configuration is recorded, and is made available for extension modules using NumPy’s C API. These are mostly defined in numpyconfig.h (included in ndarrayobject.h). The public symbols are prefixed by NPY_*. NumPy also offers some functions for querying information about the platform in use.

For private use, NumPy also constructs a config.h in the NumPy include directory, which is not exported by NumPy (that is a python extension which use the numpy C API will not see those symbols), to avoid namespace pollution.

Data type sizes#

The NPY_SIZEOF_{CTYPE} constants are defined so that sizeof information is available to the pre-processor.

NPY_SIZEOF_SHORT#

sizeof(short)

NPY_SIZEOF_INT#

sizeof(int)

NPY_SIZEOF_LONG#

sizeof(long)

NPY_SIZEOF_LONGLONG#

sizeof(longlong) where longlong is defined appropriately on the platform.

NPY_SIZEOF_PY_LONG_LONG#
NPY_SIZEOF_FLOAT#

sizeof(float)

NPY_SIZEOF_DOUBLE#

sizeof(double)

NPY_SIZEOF_LONG_DOUBLE#
NPY_SIZEOF_LONGDOUBLE#

sizeof(longdouble)

NPY_SIZEOF_PY_INTPTR_T#

Size of a pointer void * and intptr_t/Py_intptr_t.

NPY_SIZEOF_INTP#

Size of a size_t on this platform (sizeof(size_t))

Platform information#

NPY_CPU_X86#
NPY_CPU_AMD64#
NPY_CPU_IA64#
NPY_CPU_PPC#
NPY_CPU_PPC64#
NPY_CPU_SPARC#
NPY_CPU_SPARC64#
NPY_CPU_S390#
NPY_CPU_PARISC#

New in version 1.3.0.

CPU architecture of the platform; only one of the above is defined.

Defined in numpy/npy_cpu.h

NPY_LITTLE_ENDIAN#
NPY_BIG_ENDIAN#
NPY_BYTE_ORDER#

New in version 1.3.0.

Portable alternatives to the endian.h macros of GNU Libc. If big endian, NPY_BYTE_ORDER == NPY_BIG_ENDIAN, and similarly for little endian architectures.

Defined in numpy/npy_endian.h.

int PyArray_GetEndianness()#

New in version 1.3.0.

Returns the endianness of the current platform. One of NPY_CPU_BIG, NPY_CPU_LITTLE, or NPY_CPU_UNKNOWN_ENDIAN.

NPY_CPU_BIG#
NPY_CPU_LITTLE#
NPY_CPU_UNKNOWN_ENDIAN#

Compiler directives#

NPY_LIKELY#
NPY_UNLIKELY#
NPY_UNUSED#
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