Piecewise<SBasis> convole(SBasisOf<double> const &f, Interval dom_f,
SBasisOf<double> const &g, Interval dom_g,
bool f_cst_ends = false){
if ( dom_f.extent() < dom_g.extent() ) return convole(g, dom_g, f, dom_f);
Piecewise<SBasis> result;
SBasisOf<SBasisOf<double> > u,v;
u.push_back(LinearOf<SBasisOf<double> >(SBasisOf<double>(LinearOf<double>(0,1))));
v.push_back(LinearOf<SBasisOf<double> >(SBasisOf<double>(LinearOf<double>(0,0)),
SBasisOf<double>(LinearOf<double>(1,1))));
SBasisOf<SBasisOf<double> > v_u = (v - u)*(dom_f.extent()/dom_g.extent());
v_u += SBasisOf<SBasisOf<double> >(SBasisOf<double>(-dom_g.min()/dom_g.extent()));
SBasisOf<SBasisOf<double> > gg = multi_compose(g,v_u);
SBasisOf<SBasisOf<double> > ff = SBasisOf<SBasisOf<double> >(f);
SBasisOf<SBasisOf<double> > hh = integral(ff*gg,0);
result.cuts.push_back(dom_f.min()+dom_g.min());
//Note: we know dom_f.extent() >= dom_g.extent()!!
//double rho = dom_f.extent()/dom_g.extent();
double t0 = dom_g.min()/dom_f.extent();
double t1 = dom_g.max()/dom_f.extent();
double t2 = t0+1;
double t3 = t1+1;
SBasisOf<double> a,b,t;
SBasis seg;
a = SBasisOf<double>(LinearOf<double>(0,0));
b = SBasisOf<double>(LinearOf<double>(0,t1-t0));
t = SBasisOf<double>(LinearOf<double>(t0,t1));
seg = toSBasis(compose(hh,b,t)-compose(hh,a,t));
result.push(seg,dom_f.min() + dom_g.max());
if (dom_f.extent() > dom_g.extent()){
a = SBasisOf<double>(LinearOf<double>(0,t2-t1));
b = SBasisOf<double>(LinearOf<double>(t1-t0,1));
t = SBasisOf<double>(LinearOf<double>(t1,t2));
seg = toSBasis(compose(hh,b,t)-compose(hh,a,t));
result.push(seg,dom_f.max() + dom_g.min());
}
a = SBasisOf<double>(LinearOf<double>(t2-t1,1.));
b = SBasisOf<double>(LinearOf<double>(1.,1.));
t = SBasisOf<double>(LinearOf<double>(t2,t3));
seg = toSBasis(compose(hh,b,t)-compose(hh,a,t));
result.push(seg,dom_f.max() + dom_g.max());
result*=dom_f.extent();
//--constant ends correction--------------
if (f_cst_ends){
SBasis ig = toSBasis(integraaal(g))*dom_g.extent();
ig -= ig.at0();
Piecewise<SBasis> cor;
cor.cuts.push_back(dom_f.min()+dom_g.min());
cor.push(reverse(ig)*f.at0(),dom_f.min()+dom_g.max());
cor.push(Linear(0),dom_f.max()+dom_g.min());
cor.push(ig*f.at1(),dom_f.max()+dom_g.max());
result+=cor;
}
//----------------------------------------
return result;
}
