RE: operate a matrix of derivations

*To*: mathgroup at smc.vnet.net*Subject*: [mg39221] RE: [mg39184] operate a matrix of derivations*From*: F.H.Simons at tue.nl*Date*: Tue, 4 Feb 2003 02:21:54 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

When your first matrix is a matrix of functions, then the dot product results in a matrix of sums of products of arguments and functions. A simple substitution then will give you the result you are looking for. In[1]:= mat1 = {{D[#1, x] & , 0 & }, {D[#1, y] & , D[#1, x] & }} Out[1]= {{D[#1, x] & , 0 & }, {D[#1, y] & , D[#1, x] & }} In[2]:= mat2 = {{x*y, x}, {x + y, 3}} Out[2]= {{x*y, x}, {x + y, 3}} In[3]:= mat1 . mat2 /. a_.*b_Function -> b[a] Out[3]= {{y, 1}, {1 + x, 0}} Fred Simons Eindhoven University of Technology > -----Original Message----- > From: iselig at techunix.technion.ac.il To: mathgroup at smc.vnet.net > [mailto:iselig at techunix.technion.ac.il] > Sent: maandag 3 februari 2003 7:08 > To: mathgroup at smc.vnet.net > Subject: [mg39221] [mg39184] operate a matrix of derivations > > > I want to make a matrix of derivations, so I will be able to multiply > it by a matrix of functions and get the result matrix > simple example: > > |d/dx 0 | |xy x| |y 1| > | |.| |=| | > |d/dy d/dx| |x+y 3| |x+1 0| > > thank you >