def laplacian_gen(N,m,n):
rarr = sin_cos_arr(N,m,n)
rarr_laplacian = vcalc.laplacian(rarr)
X,Y = np.ogrid[0:N, 0:N]
X -= N/2; Y -= N/2
calc_laplacian = (- (1.0*m/N)**2 * np.sin(2*m*np.pi*X/N) +
(1.0*n/N)**2 * np.cos(2*n*np.pi*Y/N))
ok_(np.allclose(rarr_laplacian, calc_laplacian))
def cderiv_gen(N,m,n):
rarr = sin_cos_arr(N,m,n)
rarr_xx = vcalc.cderivative(rarr, 'X_DIR', order=2)
rarr_yy = vcalc.cderivative(rarr, 'Y_DIR', order=2)
rarr_laplacian = vcalc.laplacian(rarr)
ok_(np.allclose(rarr_laplacian, rarr_xx + rarr_yy))
