
Re: Integrate with unknow function
Posted:
Mar 24, 2013 4:16 AM


If g is the indefinite integral of a contrinuous function f[x] then
Using a replacement rule
ClearAll[f, g, expr];
expr = Integrate[f[d], {d, 0, 3}]  Integrate[f[d], {d, 0, 2}];
expr /. Integrate[f[x_], {x_, a_, b_}] > g[b]  g[a]
g[2] + g[3]
Alternatively, defining an upvalue for f (TagSet)
ClearAll[f, g, expr];
expr = Integrate[f[d], {d, 0, 3}]  Integrate[f[d], {d, 0, 2}];
f /: Integrate[f[x_], {x_, a_, b_}] = g[b]  g[a];
expr
g[2] + g[3]
Bob Hanlon
On Sat, Mar 23, 2013 at 3:25 AM, Shan <shan.pub@gmail.com> wrote: > Hi, > > I have a very rookie question as follows: > > Integrate[f[d], {d, 0,3}]  Integrate[f[d], {d, 0,2}] > > How can I get the result as f[d]? Thanks very much for any help! > > shan >

