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