def LightDotNormal(num_verts):

    normalize_rows = lambda v : col(ch.sqrt(ch.sum(v.reshape((-1,3))**2, axis=1))) / v
    sum_rows = lambda v :  ch.sum(v.reshape((-1,3)), axis=1)

    return Ch(lambda light_pos, v, vn :
        sum_rows(normalize_rows(light_pos.reshape((1,3)) - v.reshape((-1,3))) * vn.reshape((-1,3))))
dataset/ETHPy150Open mattloper/opendr/lighting.py/LightDotNormal/swapped operands of `/`