kill(all)$

van=facebook.com/LearningCalculus$

f(s,t):=%e^(-s*t)*sin(t);
f(x,y);

F(s,t):=''(integrate(f(s,t),t))$ F(s,t);

G(s):=fullratsimp(F(s,2*%pi)-F(s,0))$ G(s);

f(x,y);

G(x);