objreader_sdpa.cpp

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                           */
/* This file is part of SCIPSDP - a solving framework for mixed-integer      */
/* semidefinite programms based on SCIP.                                     */
/*                                                                           */
/* Copyright (C) 2011-2013 Discrete Optimization, TU Darmstadt               */
/*                         EDOM, FAU Erlangen-Nürnberg                       */
/*               2014-2016 Discrete Optimization, TU Darmstadt               */
/*                                                                           */
/*                                                                           */
/* This program is free software; you can redistribute it and/or             */
/* modify it under the terms of the GNU Lesser General Public License        */
/* as published by the Free Software Foundation; either version 3            */
/* of the License, or (at your option) any later version.                    */
/*                                                                           */
/* This program is distributed in the hope that it will be useful,           */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of            */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             */
/* GNU Lesser General Public License for more details.                       */
/*                                                                           */
/* You should have received a copy of the GNU Lesser General Public License  */
/* along with this program; if not, write to the Free Software               */
/* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.*/
/*                                                                           */
/*                                                                           */
/* Based on SCIP - Solving Constraint Integer Programs                       */
/* Copyright (C) 2002-2016 Zuse Institute Berlin                             */
/* SCIP is distributed under the terms of the SCIP Academic Licence,         */
/* see file COPYING in the SCIP distribution.                                */
/*                                                                           */
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*#define SCIP_DEBUG*/
/*#define SCIP_MORE_DEBUG*/

/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
#include "objreader_sdpa.h"

#include <cassert>                     // for assert
#include <cctype>                      // for isspace
#include <cstdio>                      // for printf
#include <cstdlib>                     // for abs                      /*lint !e10*//*lint !e129*/
#include <istream>                      // for istream, etc
#include <string>                       // for getline, string

#include "BlockMemoryAllocator.h"       // for BlockMemoryAllocator
#include "ScipStreamBuffer.h"           // for ScipStreamBuffer
#include "scipsdp/cons_sdp.h"           // for SCIPcreateConsSdp

#include "scip/cons_linear.h"           // for SCIPaddCoefLinear, etc
#include "scip/scip.h"                  // for SCIPinfinity, etc

/* turn off lint warnings for whole file: */
/*lint --e{788,818}*/

namespace
{

/* drop spaces and all brackets that are allowed within the blocks in the sdpa format */
   inline void drop_space(std::istream& line)
   {
      while(std::isspace(line.peek()) || line.peek() == '(' || line.peek() == '{' || line.peek() == ')' || line.peek() == '}' || line.peek() == ',')
      {
         line.ignore(1);/*lint !e747*//*lint !e534*/
      }
      return;
   }

   inline void drop_rest_line (std::istream& s)
   {
      std::string tmp;
      std::getline(s, tmp);/*lint !e534*/
      return;
   }

}

namespace scip
{

   static
   SCIP_RETCODE dropComments(
      std::istream*      file                /* the file instance that is read */
      )
   {
      char fst_col('"');
      fst_col = (*file).peek();/*lint !e734*//*lint !e838*/
      while (fst_col == '"' || fst_col == '*')
      {
         drop_rest_line(*file);
         fst_col = (*file).peek();/*lint !e734*/
      }
      return SCIP_OKAY;
   }

   /* drop spaces and all brackets that are allowed within the blocks in the sdpa format, throws an error if it reaches a newline */
   static
   SCIP_RETCODE dropSpaceNewlineError(std::istream& line)
   {
      if ( line.peek() == '\n' )
      {
         SCIPerrorMessage("Input File invalid, SDP/LP-block rows need to consist of five entries each, see data_format.txt\n");
         return SCIP_ERROR;
      }
      while(std::isspace(line.peek()) || line.peek() == '(' || line.peek() == '{' || line.peek() == ')' || line.peek() == '}' || line.peek() == ',')
      {
         line.ignore(1);/*lint !e747*//*lint !e534*/
         if ( line.peek() == '\n' )
         {
            SCIPerrorMessage("Input File invalid, SDP/LP-block rows need to consist of five entries each, see data_format.txt\n");
            return SCIP_ERROR;
         }
      }
      return SCIP_OKAY;
   }

   /* checks that only spaces, newlines or comments follow in the current line */
   static
   SCIP_RETCODE checkForLineEnd(std::istream& line)
   {
      if ( line.peek() == '\n' || line.peek() == '"' || line.peek() == '*' || line.peek() == EOF )
      {
         return SCIP_OKAY;
      }
      while(std::isspace(line.peek()) || line.peek() == '(' || line.peek() == '{' || line.peek() == ')' || line.peek() == '}' || line.peek() == ',')
      {
         line.ignore(1);/*lint !e747*//*lint !e534*/
         if ( line.peek() == '\n' || line.peek() == '"' || line.peek() == '*' || line.peek() == EOF )
         {
            return SCIP_OKAY;
         }
         else if (std::isspace(line.peek()) || line.peek() == '(' || line.peek() == '{' || line.peek() == ')' || line.peek() == '}' || line.peek() == ',')
            continue;
         else
         {
            SCIPerrorMessage("Input File invalid, SDP/LP-block rows need to consist of five entries each, see data_format.txt\n");
            return SCIP_ERROR;
         }
      }
      return SCIP_OKAY;
   }

   static
   SCIP_RETCODE testDigit(
      std::istream*      file                /* the file instance that is read */
      )
   {
      if ( (! isdigit((*file).peek())) && (! ((*file).peek() == '-')) )
      {
         SCIPerrorMessage("Input File invalid, only numerals allowed in SDP/LP-block rows, see data_format.txt\n");
         return SCIP_ERROR;
      }

      return SCIP_OKAY;
   }

   static
   SCIP_RETCODE checkIndex(
      const char*        indexname,          /* name of the index that will be used in the error message */
      int                value,              /* value to check against the upper bound */
      int                ub                  /* upper bound to check against */
      )
   {
      if ( value > ub )
      {
         SCIPerrorMessage("In an SDP/LP-block-line %s index %d was larger than given number of %ss %d.\n", indexname, value, indexname, ub);
         return SCIP_ERROR;
      }
      return SCIP_OKAY;
   }

   SCIP_RETCODE ObjReaderSDPA::scip_read(
      SCIP*              scip,               
      SCIP_READER*       reader,             
      const char*        filename,           
      SCIP_RESULT*       result              
      )
   {/*lint --e{715}*/
      *result = SCIP_DIDNOTRUN;

      int numvars;                        //Number of variables
      int numblocks;                      //Number of all blocks (SDP + LP)
      int numsdpblocks;                   //Number of SDP-blocks
      int numlpblocks;                    //Number of LP-blocks
      int alllpblocksize;                 //Size of all LP-blocks added
      int* nvarnonz;                      // nblockvarnonz[i] gives the number of nonzeros for variable i
      SCIP_Real feastol;                  // used to check for nonzeros
#ifndef NDEBUG
      int snprintfreturn;                 // to check return codes of snprintf
#endif

      std::vector<int, BlockMemoryAllocator<int> > blockpattern =
      std::vector<int, BlockMemoryAllocator<int> >(BlockMemoryAllocator<int>(scip));      //Vector with the sizes of all blocks
      std::vector<SCIP_Real> object;         //Objectivevector
      std::vector<SDPBlock> blockstruct;        //Blockstructure
      LPBlock LPData;                     //LP Data
      std::vector<bool> blockislp;         //Is the block an LP block?
      std::vector<int> intvars;           //Indices of integer variables
      std::vector <int> lp_block_num;
      std::vector <int> lp_block_size;
      int new_row_index;
      bool lp_block_already_done;

      SCIP_FILE* scip_file = SCIPfopen(filename, "r");
      if (!scip_file)
         return SCIP_READERROR;

      // setup buffer
      ScipStreamBuffer scip_buffer(scip, scip_file, true);

      // setup our stream from the new buffer
      std::istream file(&scip_buffer);

      // initialize feastol
      SCIP_CALL( SCIPgetRealParam(scip, "numerics/feastol", &feastol) );

      if( !file )
         return SCIP_READERROR;
      file.clear();

      SCIP_CALL(dropComments(&file));

      //  read numvar
      drop_space(file);
      file >> numvars;
      drop_rest_line(file);

      SCIP_CALL(dropComments(&file));

      // read numblocks
      drop_space(file);
      file >> numblocks;

      drop_rest_line(file);

      numlpblocks = 0;
      numsdpblocks = 0;
      alllpblocksize = 0;

      SCIP_CALL(dropComments(&file));

      // read block pattern
      blockpattern = std::vector<int, BlockMemoryAllocator<int> >(numblocks, 0, BlockMemoryAllocator<int>(scip));
      blockislp = std::vector<bool>(numblocks, false);/*lint !e747*//*lint !e732*/
      lp_block_num = std::vector<int>(numblocks, 0);
      lp_block_size = std::vector<int>(numblocks, 0);

      for (int j = 0; j < numblocks; ++j)
      {
         drop_space(file);
         file >> blockpattern[j];/*lint !e747*//*lint !e732*/
         if (blockpattern[j] > 0)/*lint !e747*//*lint !e732*/
         {
            numsdpblocks++;
            blockstruct.push_back(SDPBlock(blockpattern[j]));/*lint !e747*//*lint !e732*/

         }
         else if (blockpattern[j] < 0)/*lint !e747*//*lint !e732*/
         {
            //LP block has a negative coefficient!
            numlpblocks++;
            alllpblocksize += abs(blockpattern[j]);/*lint !e747*//*lint !e732*/
            blockislp[j] = true;/*lint !e747*//*lint !e732*//*lint !e1793*/
            blockstruct.push_back(SDPBlock(0));
            lp_block_num[j] = numlpblocks;/*lint !e747*//*lint !e732*/
            lp_block_size[numlpblocks - 1] = abs(blockpattern[j]);/*lint !e747*//*lint !e732*/

         }
         else
            printf("Blocklength 0 seems a bit odd, don't you think!\n");
      }

      assert(numblocks == numsdpblocks + numlpblocks);

      drop_rest_line(file);
      drop_space(file);

      SCIP_CALL(dropComments(&file));

      // read objective
      object = std::vector<SCIP_Real>(numvars, 0.0);/*lint !e747*//*lint !e732*/
      for (int i = 0; i < numvars; ++i)
      {
         file >> object[i];/*lint !e747*//*lint !e732*/
         drop_space(file);
      }

      SCIPdebugMessage("Number of variables: %d \n", numvars);
      SCIPdebugMessage("Number of blocks: %d \n", numblocks);
      SCIPdebugMessage("Number of SDP- and LP-cones: %d, %d \n", numsdpblocks, numlpblocks);


      // construct blocks

      //construct LP block
      LPData.rows = std::vector<LProw>(alllpblocksize);/*lint !e747*//*lint !e732*/
      LPData.numrows = alllpblocksize;
      SCIPdebugMessage("Number of LP constraints: %d\n", alllpblocksize);

      std::string commentline;

      // read data
      while(!file.eof())
      {
        if(file.peek() == '*') // comment
        {
                std::getline(file, commentline);/*lint !e534*/
                if (commentline.find("*INT") == 0) // if current line starts with *INT then go to Integer definitions
                {
                        drop_space(file); // drop \newline
                        break;
                }
                else // usual comment line
                {
                   drop_space(file);
                }
        }
        else
        {
                int var_index, block_index; // block id
                int row_index, col_index; // position in matrix
                SCIP_Real val;
                drop_space(file);

                SCIP_CALL( testDigit(&file) );
                file >> var_index;
                SCIP_CALL( checkIndex("variable", var_index, numvars) );
                SCIP_CALL( dropSpaceNewlineError(file) );

                SCIP_CALL( testDigit(&file) );
                file >> block_index;
                SCIP_CALL( checkIndex("block", block_index, numblocks) );
                SCIP_CALL( dropSpaceNewlineError(file) );

                SCIP_CALL( testDigit(&file) );
                file >> row_index;
                SCIP_CALL( checkIndex("row", row_index, (blockislp[block_index - 1] ? LPData.numrows : blockstruct[block_index - 1].blocksize)) );/*lint !e732*//*lint !e747*/
                SCIP_CALL( dropSpaceNewlineError(file) );

                SCIP_CALL( testDigit(&file) );
                file >> col_index;
            SCIP_CALL( checkIndex("column", col_index, (blockislp[block_index - 1] ? LPData.numrows : blockstruct[block_index - 1].blocksize)) );/*lint !e732*//*lint !e747*/
                SCIP_CALL( dropSpaceNewlineError(file) );

                SCIP_CALL( testDigit(&file) );
                file >> val;
                SCIP_CALL( checkForLineEnd(file) );

                if (SCIPisEQ(scip, val, 0.0))
                {
                        drop_rest_line(file);
                        drop_space(file);
                        continue;
                }

                //sdp-block
                if (!blockislp[block_index - 1])/*lint !e732*//*lint !e747*/
                {
                        if (row_index < col_index)
                        {
                                int save_row = row_index;
                                row_index = col_index;
                                col_index = save_row;
                        }

                        if (var_index == 0)
                        {
                                blockstruct[block_index - 1].constcolumns.push_back(col_index);/*lint !e732*//*lint !e747*/
                                blockstruct[block_index - 1].constrows.push_back(row_index);/*lint !e732*//*lint !e747*/
                                blockstruct[block_index - 1].constvalues.push_back(val);/*lint !e732*//*lint !e747*/
                                blockstruct[block_index - 1].constnum_nonzeros++;/*lint !e732*//*lint !e747*/
                        }
                        else
                        {
                                blockstruct[block_index - 1].columns.push_back(col_index);/*lint !e732*//*lint !e747*/
                                blockstruct[block_index - 1].rows.push_back(row_index);/*lint !e732*//*lint !e747*/
                                blockstruct[block_index - 1].values.push_back(val);/*lint !e732*//*lint !e747*/
                                blockstruct[block_index - 1].variables.push_back(var_index);/*lint !e732*//*lint !e747*/
                                blockstruct[block_index - 1].num_nonzeros++;/*lint !e732*//*lint !e747*/
                        }
               SCIPdebugMessage("SDP entry: block_index: %d, row: %d, col: %d, var: %d, val: %g\n", block_index, row_index, col_index, var_index,val );/*lint !e525*/
                }
                //lp-block
                else if (blockislp[block_index - 1])/*lint !e732*//*lint !e747*/
                {
                        assert(row_index == col_index);
                        if ( lp_block_num[block_index - 1] == 1 )/*lint !e732*//*lint !e747*/
                           new_row_index = row_index - 1;
                        else //we combine all lp blocks to a single one, so we add the total number of rows of earlier blocks to the row index
                        {
                           int rowoffset;
                           int b;

                           rowoffset = 0;

                           for ( b = 0; b < lp_block_num[block_index - 1] - 1; b++ )/*lint !e732*//*lint !e747*/
                              rowoffset += lp_block_size[b];/*lint !e732*//*lint !e747*/

                           new_row_index = rowoffset + row_index - 1;
                        }
                        LPData.rows[new_row_index].data.push_back(std::make_pair(var_index, val));/*lint !e732*//*lint !e747*/
                        SCIPdebugMessage("LP entry: row: %d, var: %d, val: %g\n", new_row_index, var_index,val );
                }

                drop_rest_line(file);
                drop_space(file);
        }
      }

      //read integer variables
      intvars = std::vector<int>(numvars, 0);

      while(file.peek() == '*')
      {
         int index;/*lint !e578*/
         file.ignore(1);/*lint !e534*//*lint !e747*/
         file >> index;
         //in the SDPA-file the variable numbers start at 1!
         intvars[index - 1] = 1;/*lint !e732*//*lint !e747*/
         SCIPdebugMessage("Variable %d is integer.\n", index - 1);
         drop_rest_line(file);
         drop_space(file);
      }


      /************************/
      /* create empty problem */
      /************************/

      SCIP_CALL( SCIPcreateProb(scip, filename, 0, 0, 0, 0, 0, 0, 0) );

      /*****************/
      /* add variables */
      /*****************/

      std::vector<SCIP_VAR*> VariablesX ( numvars );/*lint !e732*//*lint !e747*/

      for ( int i = 0; i < numvars; ++i)
      {
         SCIP_VAR* var;
         char      var_name[SCIP_MAXSTRLEN];
#ifndef NDEBUG
         snprintfreturn = SCIPsnprintf(var_name, SCIP_MAXSTRLEN, "X_%d", i);
         assert( snprintfreturn < SCIP_MAXSTRLEN);
#else
         (void)SCIPsnprintf(var_name, SCIP_MAXSTRLEN, "X_%d", i);
#endif


         if (intvars[i] == 1)/*lint !e732*//*lint !e747*/
         {
            SCIP_CALL( SCIPcreateVar(scip, &var, var_name, -SCIPinfinity(scip), SCIPinfinity(scip), object[i], SCIP_VARTYPE_INTEGER, TRUE, FALSE, 0, 0, 0, 0, 0));/*lint !e732*//*lint !e747*/
         }
         else
         {
            SCIP_CALL( SCIPcreateVar(scip, &var, var_name,  -SCIPinfinity(scip), SCIPinfinity(scip), object[i],
                  SCIP_VARTYPE_CONTINUOUS, TRUE, FALSE, 0, 0, 0, 0, 0));/*lint !e732*//*lint !e747*/
         }

         SCIP_CALL( SCIPaddVar(scip, var) );
         VariablesX[i] = var;/*lint !e732*//*lint !e747*/

         /* release variable for the reader. */
         SCIP_CALL( SCIPreleaseVar(scip, &var) );
      }


      /*********************************/
      /* create SDP and LP constraints */
      /*********************************/

      lp_block_already_done = false;
      for (int bindex = 0; bindex < numblocks; ++bindex)
      {
         if (!blockislp[bindex])/*lint !e732*//*lint !e747*/
         {
            int nvars;
            int nnonz;
            int blocksize;
            int* varind; /* this is used to sort the nonzeroes by variable-indices and check which variables are actually included in this block */
            int* col;
            int* row;
            SCIP_Real* val;
            int** colpointer;
            int** rowpointer;
            SCIP_Real** valpointer;
            SCIP_Var** vars;
            int constnnonz;
            int* constcol;
            int* constrow;
            SCIP_Real* constval;
            int k;
            int ind;
            int nextindaftervar;
            int firstindforvar;
            SCIP_Bool varused;

            SCIPdebugMessage("Begin construction of SDP constraint for block %d.\n", bindex);

            blocksize = blockpattern[bindex];/*lint !e732*//*lint !e747*/
            nnonz = blockstruct[bindex].num_nonzeros;/*lint !e732*//*lint !e747*/
            ind = 0;

            /* allocate memory */
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &varind, blockstruct[bindex].num_nonzeros) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &col, blockstruct[bindex].num_nonzeros) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &row, blockstruct[bindex].num_nonzeros) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &val, blockstruct[bindex].num_nonzeros) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &colpointer, numvars) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &rowpointer, numvars) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &valpointer, numvars) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &vars, numvars) );/*lint !e732*//*lint !e530*/

            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &constcol, blockstruct[bindex].constnum_nonzeros) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &constrow, blockstruct[bindex].constnum_nonzeros) );/*lint !e732*//*lint !e530*/
            SCIP_CALL( SCIPallocBlockMemoryArray(scip, &constval, blockstruct[bindex].constnum_nonzeros) );/*lint !e732*//*lint !e530*/

            /* allocate memory for nblockvarnonz & initialize it with zero */
            SCIP_CALL(SCIPallocBlockMemoryArray(scip, &nvarnonz, numvars));/*lint !e530*/
            for (int i = 0; i < numvars; i++)
               nvarnonz[i] = 0;

            /* prepare the constant arrays */
            for (k = 0; k < blockstruct[bindex].constnum_nonzeros; ++k)/*lint !e732*//*lint !e747*/
            {
               if (blockstruct[bindex].constvalues[k] > feastol || blockstruct[bindex].constvalues[k] < -feastol)/*lint !e732*//*lint !e747*/
               {
                  constcol[ind] = blockstruct[bindex].constcolumns[k] - 1;/*lint !e732*//*lint !e747*/ /* the sdpa format counts from 1 to blocksize, we want to start from 0 */
                  constrow[ind] = blockstruct[bindex].constrows[k] - 1;/*lint !e732*//*lint !e747*/
                  constval[ind] = blockstruct[bindex].constvalues[k];/*lint !e732*//*lint !e747*/
                  ind++;
               }
            }
            constnnonz = ind;

            /* prepare the non-constant arrays */
            ind = 0;
            for (k = 0; k < nnonz; ++k)
            {
               if (blockstruct[bindex].values[k] > feastol || blockstruct[bindex].values[k] < -feastol)/*lint !e732*//*lint !e747*/
               {
                  varind[ind] = blockstruct[bindex].variables[k] - 1;/*lint !e732*//*lint !e747*/
                  col[ind] = blockstruct[bindex].columns[k] - 1;/*lint !e732*//*lint !e747*/
                  row[ind] = blockstruct[bindex].rows[k] - 1;/*lint !e732*//*lint !e747*/
                  val[ind] = blockstruct[bindex].values[k];/*lint !e732*//*lint !e747*/
                  ind++;
               }
            }
            nnonz = ind;

            SCIPsortIntIntIntReal(varind, col, row, val, nnonz); /* sort the nonzeroes by non-decreasing variable indices */

            /* create the pointer arrays and insert used variables into vars-array */
            nextindaftervar = 0;
            ind = 0; /* sdp index of the current variable */
            for (k = 0; k < numvars; k++)
            {
               varused = FALSE;
               firstindforvar = nextindaftervar; /* this variable starts where the last one ended */
               while (nextindaftervar < nnonz && varind[nextindaftervar] == k) /* get the first index that doesn't belong to this variable */
               {
                  nextindaftervar++;
                  varused = TRUE;
                  nvarnonz[ind]++;
               }
               if (varused)
               {
                  vars[ind] = VariablesX[k];/*lint !e732*//*lint !e747*/ /* if the variable is used, add it to the vars array */
                  colpointer[ind] = &col[firstindforvar]; /* save a pointer to the first nonzero belonging to this variable */
                  rowpointer[ind] = &row[firstindforvar];
                  valpointer[ind] = &val[firstindforvar];
                  ind++;
               }
            }

            assert (nextindaftervar == nnonz);

            /* this was only needed to compute the vars arrays */
            SCIPfreeBlockMemoryArray(scip, &varind, blockstruct[bindex].num_nonzeros);/*lint !e747*/

            nvars = ind;

            SCIP_CONS* sdpcon;
            char       sdpcon_name[SCIP_MAXSTRLEN];
#ifndef NDEBUG
            snprintfreturn = SCIPsnprintf(sdpcon_name, SCIP_MAXSTRLEN, "SDP-Constraint-%d", bindex);
            assert( snprintfreturn < SCIP_MAXSTRLEN);
#else
            (void) SCIPsnprintf(sdpcon_name, SCIP_MAXSTRLEN, "SDP-Constraint-%d", bindex);
#endif
            SCIP_CALL( SCIPcreateConsSdp(scip, &sdpcon, sdpcon_name, nvars, nnonz, blocksize, nvarnonz, colpointer,
                  rowpointer, valpointer, vars, constnnonz, constcol, constrow, constval) );

#ifdef SCIP_MORE_DEBUG
      SCIP_CALL( SCIPprintCons(scip, sdpcon, NULL) );
#endif

            SCIP_CALL( SCIPaddCons(scip, sdpcon) );

            SCIP_CALL( SCIPreleaseCons(scip, &sdpcon) );

            /* free the used arrays */
            SCIPfreeBlockMemoryArray(scip, &nvarnonz, numvars);
            SCIPfreeBlockMemoryArray(scip, &constval, blockstruct[bindex].constnum_nonzeros);/*lint !e747*/
            SCIPfreeBlockMemoryArray(scip, &constrow, blockstruct[bindex].constnum_nonzeros);/*lint !e747*/
            SCIPfreeBlockMemoryArray(scip, &constcol, blockstruct[bindex].constnum_nonzeros);/*lint !e747*/
            SCIPfreeBlockMemoryArray(scip, &vars, numvars);
            SCIPfreeBlockMemoryArray(scip, &valpointer, numvars);
            SCIPfreeBlockMemoryArray(scip, &rowpointer, numvars);
            SCIPfreeBlockMemoryArray(scip, &colpointer, numvars);
            SCIPfreeBlockMemoryArray(scip, &val, blockstruct[bindex].num_nonzeros);/*lint !e747*/
            SCIPfreeBlockMemoryArray(scip, &row, blockstruct[bindex].num_nonzeros);/*lint !e747*/
            SCIPfreeBlockMemoryArray(scip, &col, blockstruct[bindex].num_nonzeros);/*lint !e747*/

            SCIPdebugMessage("Construction of SDP constraint for block %d completed.\n", bindex);
         }
         else
         {
            //construct lp-block only once
            if (!lp_block_already_done)
            {
               lp_block_already_done = true;
               SCIPdebugMessage("Begin construction of LP (block %d).\n", bindex);

               for (int row_i = 0; row_i < LPData.numrows; ++row_i)
               {
                  SCIP_CONS* LPcon;
                  char       LPcon_name[SCIP_MAXSTRLEN];
#ifndef NDEBUG
                  snprintfreturn = SCIPsnprintf(LPcon_name, SCIP_MAXSTRLEN, "LP-Con-%d", row_i);
                  assert( snprintfreturn < SCIP_MAXSTRLEN );
#else
                  (void) SCIPsnprintf(LPcon_name, SCIP_MAXSTRLEN, "LP-Con-%d", row_i);
#endif

                  //Get right hand side of the constraint
                  SCIP_Real LPlhs = 0.0;

                  for (unsigned int var_i = 0; var_i < LPData.rows[row_i].data.size(); ++var_i)/*lint !e732*//*lint !e747*/
                  {
                     if (LPData.rows[row_i].data[var_i].first == 0)/*lint !e732*//*lint !e747*/
                     {
                        LPlhs = LPData.rows[row_i].data[var_i].second;/*lint !e732*//*lint !e747*/
                     }
                  }

                  //Create constraint
                  SCIP_CALL( SCIPcreateConsLinear(scip, &LPcon, LPcon_name, 0, 0, 0, LPlhs, SCIPinfinity(scip), TRUE, TRUE,
                        TRUE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE));

                  SCIP_CALL( SCIPaddCons(scip, LPcon) );

                  //Insert variables into constraint:
                  for (unsigned int var_i = 0; var_i < LPData.rows[row_i].data.size(); ++var_i)/*lint !e732*//*lint !e747*/
                  {
                     if (LPData.rows[row_i].data[var_i].first != 0)/*lint !e732*//*lint !e747*/
                     {
                        SCIP_CALL( SCIPaddCoefLinear(scip, LPcon, VariablesX[LPData.rows[row_i].data[var_i].first - 1], LPData.rows[row_i].data[var_i].second) );/*lint !e732*//*lint !e747*/
                     }
                  }
#ifdef SCIP_MORE_DEBUG
                  SCIP_CALL( SCIPprintCons(scip, LPcon, NULL) );
#endif
                  SCIP_CALL( SCIPreleaseCons(scip, &LPcon) );
               }
            }
         }
      }

      *result = SCIP_SUCCESS;

      return SCIP_OKAY;
   }

}//end of namespace scip