move alloc of mumps into InitializeImpl as well

- make sure mumps_c is called with job=-1 (init) only once
- this means that mumps_mpi_communicator cannot be changed when
  reoptimizing

src/Algorithm/LinearSolvers/IpMumpsSolverInterface.cpp

@@ -92,20 +92,17 @@ MumpsSolverInterface::MumpsSolverInterface()
    DBG_START_METH("MumpsSolverInterface::MumpsSolverInterface()",
                   dbg_verbosity);
 
-   //initialize mumps
-   MUMPS_STRUC_C* mumps_ = static_cast<MUMPS_STRUC_C*>(calloc(1, sizeof(MUMPS_STRUC_C)));
-   mumps_->job = -1; //initialize mumps
-   mumps_->par = 1; //working host for sequential version
-   mumps_->sym = 2; //general symmetric matrix
-
-   mumps_ptr_ = (void*) mumps_;
+   mumps_ptr_ = NULL;
 }
 
 MumpsSolverInterface::~MumpsSolverInterface()
 {
    DBG_START_METH("MumpsSolverInterface::~MumpsSolverInterface()",
                   dbg_verbosity);
 
+   if( mumps_ptr_ == NULL )
+      return;
+
 #ifndef IPOPT_MUMPS_NOMUTEX
    const std::lock_guard<std::mutex> lock(mumps_call_mutex);
 #endif
@@ -217,27 +214,42 @@ bool MumpsSolverInterface::InitializeImpl(
    options.GetIntegerValue("mumps_scaling", mumps_scaling_, prefix);
    options.GetNumericValue("mumps_dep_tol", mumps_dep_tol_, prefix);
 
-   MUMPS_STRUC_C* mumps_ = static_cast<MUMPS_STRUC_C*>(mumps_ptr_);
+   // Reset all private data
+   initialized_ = false;
+   pivtol_changed_ = false;
+   refactorize_ = false;
+   have_symbolic_factorization_ = false;
+
+   // allocate and initialize MUMPS, if not done before
+   MUMPS_STRUC_C* mumps_;
+   if( mumps_ptr_ == NULL )
+   {
+      mumps_ = static_cast<MUMPS_STRUC_C*>(calloc(1, sizeof(MUMPS_STRUC_C)));
+
+      mumps_->job = -1; //initialize mumps
+      mumps_->par = 1; //working host for sequential version
+      mumps_->sym = 2; //general symmetric matrix
 
-   Index mpi_comm;
+      Index mpi_comm;
 #ifndef COIN_USE_MUMPS_MPI_H
-   options.GetIntegerValue("mumps_mpi_communicator", mpi_comm, prefix);
+      options.GetIntegerValue("mumps_mpi_communicator", mpi_comm, prefix);
 #else
-   mpi_comm = USE_COMM_WORLD;
+      mpi_comm = USE_COMM_WORLD;
 #endif
-   mumps_->comm_fortran = static_cast<int>(mpi_comm);
+      mumps_->comm_fortran = static_cast<int>(mpi_comm);
 
 #ifndef IPOPT_MUMPS_NOMUTEX
-   const std::lock_guard<std::mutex> lock(mumps_call_mutex);
+      const std::lock_guard<std::mutex> lock(mumps_call_mutex);
 #endif
 
-   mumps_c(mumps_);
+      mumps_c(mumps_);
 
-   // Reset all private data
-   initialized_ = false;
-   pivtol_changed_ = false;
-   refactorize_ = false;
-   have_symbolic_factorization_ = false;
+      mumps_ptr_ = (void*) mumps_;
+   }
+   else
+   {
+      mumps_ = static_cast<MUMPS_STRUC_C*>(mumps_ptr_);
+   }
 
    if( !warm_start_same_structure_ )
    {