FEI Version of the Day
fei_EqnComm.cpp
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00004 //             FEI: Finite Element Interface to Linear Solvers
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00041 */
00042 
00043 
00044 #include "fei_EqnComm.hpp"
00045 #include "fei_sstream.hpp"
00046 
00047 namespace fei {
00048 
00049 EqnComm::EqnComm(MPI_Comm comm, int numLocalEqns)
00050  : comm_(comm),
00051    globalOffsets_(2)
00052 {
00053 #ifndef FEI_SER
00054 
00055   int numProcs, localProc;
00056   MPI_Comm_size(comm, &numProcs);
00057   MPI_Comm_rank(comm, &localProc);
00058 
00059   std::vector<int> local(numProcs*2, 0);
00060   int* global = &local[0] + numProcs;
00061 
00062   if (numLocalEqns < 0) {
00063     throw std::runtime_error("fei::EqnComm ERROR, negative numLocalEqns not allowed.");
00064   }
00065 
00066   local[localProc] = numLocalEqns;
00067 
00068   MPI_Allreduce(&local[0], global, numProcs, MPI_INT, MPI_MAX, comm_);
00069 
00070   globalOffsets_.resize(numProcs+1);
00071 
00072   int offset = 0;
00073   for(int i=0; i<numProcs; ++i) {
00074     globalOffsets_[i] = offset;
00075     offset += global[i];
00076   }
00077   globalOffsets_[numProcs] = offset;
00078 
00079 #else
00080   globalOffsets_[0] = 0;
00081   globalOffsets_[1] = numLocalEqns;
00082 #endif
00083 }
00084   
00085 EqnComm::~EqnComm()
00086 {
00087 }
00088 
00089 const std::vector<int>&
00090 EqnComm::getGlobalOffsets() const
00091 {
00092   return(globalOffsets_);
00093 }
00094 
00095 int
00096 EqnComm::getOwnerProc(int eqn) const
00097 {
00098 //  std::vector<int>::const_iterator
00099 //   iter = std::lower_bound(globalOffsets_.begin(), globalOffsets_.end(),
00100 //                           eqn);
00101 //  int proc = iter - globalOffsets_.begin() - 1;
00102 //  if (*iter==eqn) ++proc;
00103   int proc = 0;
00104   for(unsigned p=1; p<globalOffsets_.size(); ++p) {
00105     if (eqn < globalOffsets_[p]) {
00106       proc = p-1;
00107       break;
00108     }
00109   }
00110 
00111 #ifndef NDEBUG
00112   int numProcs = globalOffsets_.size()-1;
00113   if (proc >= numProcs) {
00114     FEI_OSTRINGSTREAM osstr;
00115     osstr << "fei::EqnComm::getOwnerProc: input eqn="<<eqn<<", proc="<<proc
00116       << ", ERROR, proc should be in [0.."<<numProcs-1<<"].";
00117     throw std::runtime_error(std::string(osstr.str().c_str()));
00118   }
00119 #endif
00120 
00121   return((int)proc);
00122 }
00123 
00124 }//namespace fei
00125 
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