       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:= D[Product[f[k,z],{k,0,m}],{z,n}]
>
> Out= 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:=
Product[f[k, z], {k, 0, m}]

Out=
Product[f[k, z], {k, 0, m}]

Compare with

In:=
f[a_, b_] := b*Cos[a]

In:=
Product[f[k, z], {k, 0, 2}]

Out=
3
z  Cos Cos

In:=
D[Product[f[k, z], {k, 0, 2}], {z, 1}]

Out=
2
3 z  Cos Cos

HTH,
Jean-Marc

```

• Prev by Date: Re: Problem with derivate of product
• Next by Date: Re: Mathematica bugs?
• Previous by thread: Re: Problem with derivate of product
• Next by thread: SetAccuracy formatting question