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_LONG_LONG

sizeof(longlong) where longlong is defined appropriately on the platform (A macro defines NPY_SIZEOF_LONGLONG as well.)

NPY_SIZEOF_PY_LONG_LONG

NPY_SIZEOF_FLOAT

sizeof(float)

NPY_SIZEOF_DOUBLE

sizeof(double)

NPY_SIZEOF_LONG_DOUBLE

sizeof(longdouble) (A macro defines NPY_SIZEOF_LONGDOUBLE as well.)

NPY_SIZEOF_PY_INTPTR_T

Size of a pointer on this platform (sizeof(void *)) (A macro defines NPY_SIZEOF_INTP as well.)

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.

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.