test12.py

from __future__ import print_function
import pytest
import numpy as N
import time
from instant import inline_with_numpy


def test_grid_loop():

    func_str = "sin"
    c_code = """
void gridloop(int x1, int y1, double* a,
              int n, double* x,
              int m, double* y) {
  for (int i=0; i<n; i++) {
      for (int j=0; j<m; j++) {
          a[i*n +j] = %s(x[i] + y[j]);
      }
  }
}
    """ % func_str

    n = 5000

    a = N.zeros([n, n])
    x = N.arange(0.0, n, 1.0)
    y = N.arange(0.0, n, 1.0)

    arrays = [['x1', 'y1', 'a'], ['n', 'x'], ['m', 'y']]
    grid_func = inline_with_numpy(c_code, arrays=arrays )


    t1 = time.time()
    grid_func(a, x, y)
    t2 = time.time()
    print('With instant:', t2-t1, 'seconds')


    xv = x[:, N.newaxis]
    yv = y[N.newaxis,:]
    a2 = N.zeros([n, n])
    t1 = time.time()
    a2[:,:] = N.sin(xv + yv)
    t2 = time.time()
    print('With numpy:', t2-t1, 'seconds')

    d = a-a2
    d.shape = (n*n,)

    assert abs(max(d)) < 1.0e-12