Tutorial slides (PDF) - Clemson University

Python BLAS Interface
void dscal_(int*n, double* alpha, double* x, int* incx); % C prototype for Fortran
void zscal_(int*n, void* alpha, void* x, int* incx); % C prototype for Fortran
#define DOUBLEP(a) ((double*)((a)->data)) % Casting for NumPy data struc.
#define COMPLEXP(a) ((double_complex*)((a)->data)) % Casting for NumPy data struc.
PyObject* scal(PyObject *self, PyObject *args)
{
Py_complex alpha;
PyArrayObject* x;
if (!PyArg_ParseTuple(args, "DO", &alpha, &x))
return NULL;
int n = x->dimensions[0];
for (int d = 1; d < x->nd; d++) % NumPy arrays can be multi-dimensional!
n *= x->dimensions[d];
int incx = 1;
}
if (x->descr->type_num == PyArray_DOUBLE)
dscal_(&n, &(alpha.real), DOUBLEP(x), &incx);
else
zscal_(&n, &alpha, (void*)COMPLEXP(x), &incx);
Py_RETURN_NONE;