Re: Problem with derivate of product
- To: mathgroup at smc.vnet.net
- Subject: [mg67322] Re: Problem with derivate of product
- From: Peter Pein <petsie at dordos.net>
- Date: Sun, 18 Jun 2006 05:13:15 -0400 (EDT)
- References: <e70fid$rmp$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Esa A E Peuha schrieb:
> 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?
>
Hi Esa,
I don't know what's going on there, but
pfn = Derivative[n][Product[f[k, #1], {k, 0, m}] & ][z]
Derivative[n][Product[f[k, #1], {k, 0, m}] & ][z]
seems to be a workaround:
Expand[pfn /. {f -> (1 + #2/(1 + #1) & ), m -> 5, n -> 2}]
203/45 + (49*z)/8 + (35*z^2)/12 + (7*z^3)/12 + z^4/24
Expand[D[Times @@ (1 + z/(1 + #1) & ) /@ Range[0, 5], {z, 2}]]
203/45 + (49*z)/8 + (35*z^2)/12 + (7*z^3)/12 + z^4/24
Peter