Date: Nov 21, 2012 1:15 AM
Author: Tang Laoya
Subject: How to calculate the partial derivative?

Dear all,

I am trying to calculate the partial derivative by mathematica, I have the following commands:
L1=a1+b1*x+c1*y;
L2=a2+b2*x+c2*y;
L3=a3+b3*x+c3*y;

NN=L1*L2;

DNx=D[NN,x];

I got the following result:
DNex=b2 (a1+b1 x+c1 y)+b1 (a2+b2 x+c2 y)

How to do to have the following result?

DNex=b2*L1 + b1 * L2


Thanks,
Tang Laoya