gridloop2 in C; more macros

Check the dimensions of a NumPy array:

#define NDIMCHECK(a, expected_ndim) \
  if (a->nd != expected_ndim) { \
    PyErr_Format(PyExc_ValueError, \
    "%s array is %d-dimensional, expected to be %d-dimensional",\
		 QUOTE(a), a->nd, expected_ndim); \
    return NULL; \
  }

Application:

NDIMCHECK(xcoor, 1); TYPECHECK(xcoor, PyArray_DOUBLE);

If xcoor is 2-dimensional, an exceptions is raised by NDIMCHECK:

exceptions.ValueError 
xcoor array is 2-dimensional, but expected to be 1-dimensional