void
v_coef(SBasis2d f, unsigned deg, SBasis &a, SBasis &b) {
a = SBasis();
b = SBasis();
for (unsigned u=0; u<f.us; u++){
a.push_back(Linear(f.index(deg,u)[0], f.index(deg,u)[1]));
b.push_back(Linear(f.index(deg,u)[2], f.index(deg,u)[3]));
}
}
//see a sb2d as an sb of u with coef in sbasis of v.
void
u_coef(SBasis2d f, unsigned deg, SBasis &a, SBasis &b) {
a = SBasis();
b = SBasis();
for (unsigned v=0; v<f.vs; v++){
a.push_back(Linear(f.index(deg,v)[0], f.index(deg,v)[2]));
b.push_back(Linear(f.index(deg,v)[1], f.index(deg,v)[3]));
}
}
SBasis extract_u(SBasis2d const &a, double u) {
SBasis sb;
double s = u*(1-u);
for(unsigned vi = 0; vi < a.vs; vi++) {
double sk = 1;
Linear bo(0,0);
for(unsigned ui = 0; ui < a.us; ui++) {
bo += (extract_u(a.index(ui, vi), u))*sk;
sk *= s;
}
sb.push_back(bo);
}
return sb;
}
