Re: Problem with derivate of product

*To*: mathgroup at smc.vnet.net*Subject*: [mg67315] Re: Problem with derivate of product*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Sun, 18 Jun 2006 05:13:00 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <e70fid$rmp$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Esa A E Peuha wrote: > Mathematica 5.0 seems to have trouble with parsing this input: > > In[1]:= D[Product[f[k,z],{k,0,m}],{z,n}] > > Out[1]= D[Product[f[k, z], {k, 0, m}], z] > > Has this been fixed in newer versions? > What output do you expect? Since f is not defined, the product is returned unevaluated: In[2]:= Product[f[k, z], {k, 0, m}] Out[2]= Product[f[k, z], {k, 0, m}] Compare with In[5]:= f[a_, b_] := b*Cos[a] In[6]:= Product[f[k, z], {k, 0, 2}] Out[6]= 3 z Cos[1] Cos[2] In[7]:= D[Product[f[k, z], {k, 0, 2}], {z, 1}] Out[7]= 2 3 z Cos[1] Cos[2] HTH, Jean-Marc