Cython Cimport无法解析的外部符号 [英] Cython Cimport unresolved external symbol

问题描述

我的setup.py是：

My setup.py are :

from distutils.core import setup
from distutils.extension import Extension
from Cython.Build import cythonize
import numpy as np

extensions = [
    Extension('_hmmc', ['_hmmc.pyx'], include_dirs = [np.get_include()]),
    ]

setup(
    ext_modules = cythonize(extensions)
    )

，而我正在尝试使用cimport使其正常工作。

and I'm experimenting with cimport to get it to work.

from numpy.math cimport expl

import numpy as np
print(expl(5-2))

但是，错误是

错误LNK2001：无法解析的外部符号_npy_expl

error LNK2001: unresolved external symbol _npy_expl

有什么想法吗？我检查了我的cython / includes / numpy / math.pxd是否具有以下内容：

Any idea? I have checked that my cython/includes/numpy/math.pxd had this:

long double expl npy_expl（long double x）

long double expl "npy_expl"(long double x)

有什么想法吗？

推荐答案

可能为了简单起见，可以使用标准库中的 exp ，否则会有一些麻烦，以使其与 npy_expl一起使用。

Probably to keep it simple, one could use exp from the standard library, otherwise there are some hoops to jump through, to get it work with npy_expl.

通常的Numpy-API仅用于标头（更准确地说，在编译/链接时仅需要标头，请参见此处），但数学函数并非如此。有定义 NPY_INLINE_MATH ，它也可以将numpy的数学库显示为内联函数，但这不适用于已安装的numpy-distributionen，因为它们缺少 core / src 文件夹，其中给出了数学函数的定义。

The usual Numpy-API is header-only (more precisely, only headers are needed at compile-/linktime, see here), but this is not the case with math-functions. There is define NPY_INLINE_MATH, which would also present numpy's math library as inline functions, but this will not work on installed numpy-distributionen, because those lack the core/src-folder, where the definitions of math-functions are given.

因此，您必须添加预编译的静态numpy的数学库设置。可以在文件夹 core / lib 中找到它，并且至少在Linux上称为 libnpymath.a 。

So you have to add the precompiled static numpy's math library to your setup. It can be found in folder core/lib and is called (at least on linux) libnpymath.a.

最可靠的方法是使用 numpy.distutils.misc_util get_info $ c>，返回一个字典，该字典提供'define_macros'，
'include_dirs'，'libraries'和'library_dirs'-即我们需要传递给扩展的值，例如

The most robust way is to use get_info from numpy.distutils.misc_util, which returns a dictionary providing values for 'define_macros', 'include_dirs', 'libraries' and 'library_dirs' - i.e. values we need to pass to Extension, e.g.

from distutils.core import setup
from distutils.extension import Extension
from Cython.Build import cythonize

from numpy.distutils.misc_util import get_info
npymath_info = get_info('npymath')

extensions = [
    Extension('_hmmc', ['_hmmc.pyx'],
               **npymath_info 
               ),
    ]

setup(
    ext_modules = cythonize(extensions)
    )

---

还有函数 get_mathlibs numpy.distutils.misc_util 的$ c>，但仅当存在 _numpyconfig.h 时才起作用，而不是至少在我的安装中。

---

There is also the function get_mathlibs from numpy.distutils.misc_util but it only works if _numpyconfig.h is present, which is not the case at least in my installation.

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