python - 直接从 C 调用 mpmath

Question

我想从 C 代码访问 mpmath 的特殊函数。我知道如何通过中间 python 脚本来做到这一点。例如，为了计算超几何函数，C 程序:

#include <Python.h>

void main (int argc, char *argv[])
{
   int npars= 4;
   double a1, a2, b1, x, res;
   PyObject *pName, *pModule, *pFunc, *pArgs, *pValue;
   PyObject *pa1, *pa2, *pb1, *px;

   a1= atof(argv[1]);
   a2= atof(argv[2]);
   b1= atof(argv[3]);
   x= atof(argv[4]);

   setenv("PYTHONPATH", ".", 1); // Set PYTHONPATH TO bin directory
   Py_Initialize();

   pa1= PyFloat_FromDouble(a1);
   pa2= PyFloat_FromDouble(a2);
   pb1= PyFloat_FromDouble(b1);
   px=  PyFloat_FromDouble(x);
   pName = PyString_FromString("GGauss_2F1");
   pModule = PyImport_Import(pName);
   pFunc = PyObject_GetAttrString(pModule, "Gauss_2F1");
   pArgs = PyTuple_Pack(npars, pa1, pa2, pb1, px);
   pValue = PyObject_CallObject(pFunc, pArgs);

   res= PyFloat_AsDouble(pValue);
   printf("2F1(x)= %.15f\n", res);
}

通过调用 GGauss_2F1.py 脚本可以正常工作:

from mpmath import *
def Gauss_2F1(a1, a2, b1, z):
   hpg= hyp2f1(a1, a2, b1, z)
   return hpg

有没有办法直接从 C 调用 mpmath 函数 hyp2f1，而无需借助中间的 python 脚本？我猜测mpmath模块可以通过命令导入

PyRun_SimpleString("from mpmath import *");   

但是我如何访问实际的函数呢？

Answer 1

What? No! Literally do the things you did to access GGauss_2F1.Gauss_2F1, just with the names changed. Why are you trying to PyRun_SimpleString("from mpmath import *")? – user2357112

好的。按照您的建议:

#include <Python.h>

void main (int argc, char *argv[])
{
   int npars= 4;
   double a1, a2, b1, x, res;
   PyObject *pName, *pModule, *pFunc, *pArgs, *pValue;
   PyObject *pa1, *pa2, *pb1, *px;

   a1= atof(argv[1]);
   a2= atof(argv[2]);
   b1= atof(argv[3]);
   x= atof(argv[4]);

   setenv("PYTHONPATH", ".", 1); // Set PYTHONPATH TO bin directory
   Py_Initialize();

   pa1= PyFloat_FromDouble(a1);
   pa2= PyFloat_FromDouble(a2);
   pb1= PyFloat_FromDouble(b1);
   px=  PyFloat_FromDouble(x);
   pName = PyString_FromString("mpmath");
   pModule = PyImport_Import(pName);
   pFunc = PyObject_GetAttrString(pModule, "hyp2f1");
   pArgs = PyTuple_Pack(npars, pa1, pa2, pb1, px);
   pValue = PyObject_CallObject(pFunc, pArgs);

   res= PyFloat_AsDouble(pValue);
   printf("2F1(x)= %.15f\n", res);
}

代码似乎按预期工作并且正在生成正确的结果。感谢您的“耐心”...