Changing order of integration/summation



Is it something that I need to do to declare some variables as being
constants, perhaps?

Cheers
JP

Robert Dodier wrote:
> On 9/1/08, John Pye <john.pye at anu.edu.au> wrote:
>
>   
>>  cp0(tau) := subst(%Tc/tau,T,sum(%a(i)*tau^i,i,0,n) +
>>  sum(%b(i)*(%beta(i)/T)^2*exp(%beta(i)/T)/(exp(%beta(i)/T)-1)^2,i,0,m))
>>
>>  Now, I want to calculate the following:
>>
>>  -tau/R*integrate(1/tau^2*cp0(tau), tau) + 1/R*integrate(1/tau*cp0(tau),tau)
>>
>>  Problem is that when this evaluates, it keeps the integral signs, rather
>>  than actually evaluating and expanding and simplifying.
>>     
>
> Hmm, I thought maybe declare(integrate, linear); expand(<whatever>);
> would do it, but that doesn't cause integrate to distribute over sum.
> Can anyone think of a simple way to do it? I have some other ideas
> about messier stuff.
>
> best
>
> Robert Dodier
>