Question

我正在尝试将scipy.integrate.nquad与ctypes函数一起使用。我完全按照Faster integration using Ctypes上的说明进行操作。

ctypes集成可以通过几个简单的步骤完成：
使用函数签名double f(int n, double args[n])在C中编写一个被积函数，其中args是一个包含函数f的参数的数组。
//testlib.c

double f(int n, double args[n])    
{
   return args[0] - args[1] * args[2]; //corresponds to x0 - x1 * x2
}
现在将此文件编译为共享/动态库（快速搜索将有助于此，因为它取决于操作系统）。用户必须链接任何使用的数学库等。在Linux上，这看起来像：
$ gcc -shared -o testlib.so -fPIC testlib.c
输出库将被称为testlib.so，但它可能具有不同的文件扩展名。现在已经创建了一个库，可以使用ctypes加载到Python中。
使用ctypes将共享库加载到Python中并设置restypes和argtypes - 这允许Scipy解释函数   正确地：
>>> import ctypes

>>> from scipy import integrate

>>> lib = ctypes.CDLL('/**/testlib.so') # Use absolute path to testlib

>>> func = lib.f # Assign specific function to name func (for simplicity)

>>> func.restype = ctypes.c_double

>>> func.argtypes = (ctypes.c_int, ctypes.c_double)
请注意，无论参数的数量如何，argtypes始终为(ctypes.c_int, ctypes.c_double)，并且restype始终为ctypes.c_double。
现在正常使用nquad：
集成库函数
>>> integrate.nquad(func, [[0,10],[-10,0],[-1,1]])

(1000.0, 1.1102230246251565e-11)

然而，在最后一步，我没有得到积分的结果，而是出现以下错误：

>>> integrate.nquad(func,[[0,1.0],[-2.0,3.0],[1.0,2.0]])

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 618, in nquad
      return _NQuad(func, ranges, opts).integrate(*args)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 670, in integrate

    value, abserr = quad(f, low, high, args=args, **opt)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 254, in quad

    retval = _quad(func,a,b,args,full_output,epsabs,epsrel,limit,points)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 319, in _quad

    return _quadpack._qagse(func,a,b,args,full_output,epsabs,epsrel,limit)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 670, in integrate

    value, abserr = quad(f, low, high, args=args, **opt)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 254, in quad

    retval = _quad(func,a,b,args,full_output,epsabs,epsrel,limit,points)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 319, in _quad

    return _quadpack._qagse(func,a,b,args,full_output,epsabs,epsrel,limit)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 670, in integrate

    value, abserr = quad(f, low, high, args=args, **opt)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 254, in quad

    retval = _quad(func,a,b,args,full_output,epsabs,epsrel,limit,points)

  File "/home/bfn097/apps/scipy/0.13.3_mkl-11.1.2_gcc-4.4.7/lib64/python/scipy/integrate/quadpack.py", line 319, in _quad

    return _quadpack._qagse(func,a,b,args,full_output,epsabs,epsrel,limit)

quadpack.error: quad: first argument is a ctypes function pointer with incorrect signature

我使用的是gcc-4.4.7，python 2.6.6，numpy-1.7.1，scipy-0.13.3

Answer 1

参数的类型应为：ctypes.POINTER(ctypes.c_double)

但您考虑使用cffi吗？除了比ctypes更快之外，你也不必亲自编写参数内容，只需复制C声明并让cffi解析它们。

scipy.integrate.quad ctypes函数错误＆＃34; quadpack.error：quad：第一个参数是一个带有错误签名的ctypes函数指针＆＃34;

1 个答案: