On 04/14/2017 04:21 AM, Peter Otten wrote: > Stephen P. Molnar wrote: > >> However, what I want to do is multiply each element ob D by each element >> of s and sum all of the products. > > If you *really* want this: > > sum_of_all_products = s.sum() * D.sum() > > example: > > s = [a b c] > > D = [[a1 a2] > [a3 a4]] > > a*a1 + a*a2 + a*a3 + a*a4 = a * D.sum() > > d := D.sum() > a*d + b*d + c*d = s.sum() * d > > Even if that's what you want you should heed Steven's advice. >
Nice example on "analyze before computing". Nevertheless, A lazy man's approach to life might go using numpy ufunc.outer [ https://docs.scipy.org/doc/numpy/reference/generated/numpy.ufunc.outer.html ] In [1]: import numpy as np In [2]: from sympy import symbols In [3]: x1, y1, z1, x2, y2, z2, x3, y3, z3 = symbols('x1 y1 z1 x2 y2 z2 x3 y3 z3 ...: ') In [4]: x=np.array([[x1,y1,z1], [x2,y2,z2], [x3,y3,z3]]) In [5]: z=np.array([z1,z2,z3]) In [6]: print(np.multiply.outer(z,x)) [[[x1*z1 y1*z1 z1**2] [x2*z1 y2*z1 z1*z2] [x3*z1 y3*z1 z1*z3]] [[x1*z2 y1*z2 z1*z2] [x2*z2 y2*z2 z2**2] [x3*z2 y3*z2 z2*z3]] [[x1*z3 y1*z3 z1*z3] [x2*z3 y2*z3 z2*z3] [x3*z3 y3*z3 z3**2]]] In [7]: np.multiply.outer(z,x).sum() Out[7]: x1*z1 + x1*z2 + x1*z3 + x2*z1 + x2*z2 + x2*z3 + x3*z1 + x3*z2 + x3*z3 + y1*z1 + y1*z2 + y1*z3 + y2*z1 + y2*z2 + y2*z3 + y3*z1 + y3*z2 + y3*z3 + z1**2 + 2*z1*z2 + 2*z1*z3 + z2**2 + 2*z2*z3 + z3**2 In [8]: Sergio https://www.packtpub.com/big-data-and-business-intelligence/numerical-and-scientific-computing-scipy-video https://github.com/rojassergio/Learning-Scipy _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
