def define_structure(size):
structure = np.zeros([size,size])
dmat,d= mi.distance_matrix(size/2.-0.5,size/2.-0.5,structure)
structure[dmat<size/2]=1
return structure
def compute_magnitude(image,xc,yc,aperture,magzero,exptime=1.0):
dmat = mi.distance_matrix(xc,yc,image)[0]
in_aperture = (dmat<aperture)
tot_flux = np.sum(image[in_aperture])
mag = -2.5*np.log10(tot_flux/exptime)+magzero
return mag