Re: Integrate not very aggressive about taking constants out of integrals

*To*: mathgroup at smc.vnet.net*Subject*: [mg81427] Re: Integrate not very aggressive about taking constants out of integrals*From*: dimitris <dimmechan at yahoo.com>*Date*: Sun, 23 Sep 2007 04:30:02 -0400 (EDT)*References*: <fd2g2d$s61$1@smc.vnet.net>

On 22 , 10:26, "Darryl Yong" <darryly... at gmail.com> wrote: > Try the following three few lines of code in Mathematica: > > temp1 = Integrate[-Exp[p[s]] , {s,0,t}]; > temp2 = Integrate[Exp[p[s]] , {s,0,t}]; > temp1+temp2 > > Out[3] = Integrate[-E^p[s], {s, 0, t}] + Integrate[E^p[s], {s, 0, t}] > > FullSimplify[temp1+temp2] > > Out[4] = Integrate[-E^p[s], {s, 0, t}] + Integrate[E^p[s], {s, 0, t}] > > You'll notice that Mathematica doesn't take the negative sign out of > the integral in temp1, so the result of temp1+temp2 is not zero unless > you define something for p[s] and let it actually work out both > integrals. > > Does anyone know of a way to help Mathematica be more aggressive about > taking constants out of integrals? > > Thanks, Darryl Hi. How about? In[42]:= temp1 = Integrate[-Exp[p[s]], {s, 0, t}]; temp2 = Integrate[Exp[p[s]], {s, 0, t}]; In[49]:= temp1 + temp2 /. t -> 0 Out[49]= 0 and In[45]:= D[temp1 + temp2, t] Out[45]= 0 Cheers Dimitris