lily/qlp.cc

   1 /*
   2   qlp.cc -- implement Mixed_qp
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c)  1997--1998 Han-Wen Nienhuys <hanwen@stack.nl>
   7 */
   8
   9 #include "debug.hh"
  10 #include "qlp.hh"
  11
  12
  13 void
  14 Mixed_qp::add_equality_cons (Vector , double)
  15 {
  16   assert (false);
  17 }
  18
  19 void
  20 Mixed_qp::add_fixed_var (int i, Real r)
  21 {
  22   eq_cons.push (i);
  23   eq_consrhs.push (r);
  24 }
  25
  26
  27 /**
  28   eliminate appropriate variables, until we have a Ineq_constrained_qp
  29   then solve that.
  30
  31   PRE
  32   cons should be ascending
  33   */
  34 Vector
  35 Mixed_qp::solve (Vector start) const
  36 {
  37   if (!dim())
  38     return Vector (0);
  39
  40   print();
  41   Ineq_constrained_qp pure (*this);
  42
  43   for  (int i= eq_cons.size()-1; i>=0; i--)
  44     {
  45       pure.eliminate_var (eq_cons[i], eq_consrhs[i]);
  46       start.del (eq_cons[i]);
  47     }
  48   Vector sol = pure.solve (start);
  49   for (int i= 0; i < eq_cons.size(); i++)
  50     {
  51       sol.insert (eq_consrhs[i],eq_cons[i]);
  52     }
  53   return sol;
  54 }
  55
  56
  57 void
  58 Ineq_constrained_qp::assert_solution (Vector sol) const
  59 {
  60   Array<int> binding;
  61   for (int i=0; i < cons_.size(); i++)
  62     {
  63       Real R=cons_[i] * sol- consrhs_[i];
  64       assert (R> -EPS);
  65       if (R < EPS)
  66         binding.push (i);
  67     }
  68   // KKT check...
  69   // todo
  70 }
  71
  72 void
  73 Ineq_constrained_qp::print() const
  74 {
  75 #ifndef NPRINT
  76   DOUT << "Quad " << quad_;
  77   DOUT << "lin " << lin_ <<"\n"
  78        << "const " << const_term_<<"\n";
  79   for (int i=0; i < cons_.size(); i++)
  80     {
  81       DOUT << "constraint["<<i<<"]: " << cons_[i] << " >= " << consrhs_[i];
  82       DOUT << "\n";
  83     }
  84 #endif
  85 }
  86
  87 Mixed_qp::Mixed_qp (int n)
  88   : Ineq_constrained_qp (n)
  89 {
  90 }
  91
  92 void
  93 Mixed_qp::OK() const
  94 {
  95 #ifndef NDEBUG
  96   Ineq_constrained_qp::OK();
  97   assert (eq_consrhs.size() == eq_cons.size ());
  98 #endif
  99 }
 100
 101 void
 102 Mixed_qp::print() const
 103 {
 104 #ifndef NPRINT
 105   Ineq_constrained_qp::print();
 106   for (int i=0; i < eq_cons.size(); i++)
 107     {
 108       DOUT << "eq cons "<<i<<": x["<<eq_cons[i]<<"] == " << eq_consrhs[i]<<"\n";
 109     }
 110 #endif
 111 }
 112