Have to retain dedicated triangularToSquareHessian for QPASM solver

Author: jajhall

highs/lp_data/Highs.cpp

@@ -3960,8 +3960,9 @@ HighsStatus Highs::callSolveLp(HighsLp& lp, const string message) {
 HighsStatus Highs::callSolveQp() {
   // Check that the model is column-wise
   HighsLp& lp = model_.lp_;
-  HighsHessian& hessian = model_.hessian_;
   assert(model_.lp_.a_matrix_.isColwise());
+  HighsHessian& hessian = model_.hessian_;
+  assert(hessian.format_ == HessianFormat::kTriangular);
   if (hessian.dim_ > lp.num_col_) {
     highsLogDev(
         options_.log_options, HighsLogType::kError,

highs/model/HighsHessianUtils.cpp

@@ -260,6 +260,15 @@ void triangularToSquareHessian(const HighsHessian& hessian,
     return;
   }
   assert(hessian.format_ == HessianFormat::kTriangular);
+  // Cannot use the following, since it puts the diagonal entry first
+  // in each column and, strangely, the active set QP solver seems to
+  // need the entries column-by-column in row order
+  /*
+  HighsHessian square_hessian = hessian.toSquare();
+  std::vector<HighsInt> nw_start = square_hessian.start_;
+  std::vector<HighsInt> nw_index = square_hessian.index_;
+  std::vector<double> nw_value = square_hessian.value_;
+  */
   const HighsInt nnz = hessian.start_[dim];
   const HighsInt square_nnz = nnz + (nnz - dim);
   start.resize(dim + 1);