Merge pull request ERGO-Code#1586 from ERGO-Code/fix-1584-master

Applied fix-1584 mods to update master

check/TestLpModification.cpp

@@ -1,13 +1,14 @@
 #include "Avgas.h"
 #include "HCheckConfig.h"
 #include "Highs.h"
+#include "SpecialLps.h"
 #include "catch.hpp"
 #include "lp_data/HighsLpUtils.h"
 #include "util/HighsRandom.h"
 #include "util/HighsUtils.h"
 
 const bool dev_run = false;
-const double inf = kHighsInf;
+// const double inf = kHighsInf;
 const double double_equal_tolerance = 1e-5;
 void HighsStatusReport(const HighsLogOptions& log_options, std::string message,
                        HighsStatus status);
@@ -1874,3 +1875,56 @@ TEST_CASE("mod-duplicate-indices", "[highs_data]") {
   REQUIRE(objective0 < objective1);
   REQUIRE(objective0 == -7.75);
 }
+
+TEST_CASE("resize-integrality", "[highs_data]") {
+  Highs highs;
+  highs.setOptionValue("output_flag", dev_run);
+  SpecialLps special_lps;
+  HighsLp lp;
+  HighsModelStatus require_model_status;
+  double optimal_objective;
+  special_lps.distillationLp(lp, require_model_status, optimal_objective);
+  HighsInt original_num_col = lp.num_col_;
+  for (HighsInt k = 0; k < 4; k++) {
+    // k = 0: Add continuous column to LP, so final integrality.size() should be
+    // 0
+    //
+    // k = 1: Add continuous column to IP, so final integrality.size() should be
+    // full
+    //
+    // k = 2: Add integer column to LP, so final integrality.size() should be
+    // full
+    //
+    // k = 3: Add integer column to IP, so final integrality.size() should be
+    // full
+    if (k == 1 || k == 3) {
+      lp.integrality_.assign(original_num_col, HighsVarType::kInteger);
+    } else {
+      lp.integrality_.clear();
+    }
+    REQUIRE(highs.passModel(lp) == HighsStatus::kOk);
+    REQUIRE(highs.getNumCol() == original_num_col);
+    double cost = 0.0;
+    double lower = 0.0;
+    double upper = 1.0;
+    highs.addCols(1, &cost, &lower, &upper, 0, nullptr, nullptr, nullptr);
+    const std::vector<HighsVarType>& integrality = highs.getLp().integrality_;
+    if (k == 0 || k == 2) {
+      // Model is LP
+      REQUIRE(int(integrality.size()) == 0);
+    } else {
+      // Model is MIP
+      REQUIRE(int(integrality.size()) == int(original_num_col + 1));
+    }
+    if (k >= 2)
+      REQUIRE(highs.changeColIntegrality(2, HighsVarType::kInteger) ==
+              HighsStatus::kOk);
+    if (k == 0) {
+      // Model is LP
+      REQUIRE(int(integrality.size()) == 0);
+    } else {
+      // Model is MIP
+      REQUIRE(int(integrality.size()) == int(original_num_col + 1));
+    }
+  }
+}

check/TestLpSolvers.cpp

@@ -279,7 +279,7 @@ TEST_CASE("LP-solver", "[highs_lp_solver]") {
   const HighsInfo& info = highs.getInfo();
   REQUIRE(info.num_dual_infeasibilities == 0);
 
-  REQUIRE(info.simplex_iteration_count == 472); //476);  // 444);
+  REQUIRE(info.simplex_iteration_count == 472);  // 476);  // 444);
 
   HighsModelStatus model_status = highs.getModelStatus();
   REQUIRE(model_status == HighsModelStatus::kOptimal);
@@ -292,7 +292,7 @@ TEST_CASE("LP-solver", "[highs_lp_solver]") {
   return_status = highs.run();
   REQUIRE(return_status == HighsStatus::kOk);
 
-  REQUIRE(info.simplex_iteration_count == 592); //621);  // 584);  //
+  REQUIRE(info.simplex_iteration_count == 592);  // 621);  // 584);  //
 }
 
 TEST_CASE("mip-with-lp-solver", "[highs_lp_solver]") {

src/lp_data/HighsLpUtils.cpp

@@ -1419,6 +1419,11 @@ void appendColsToLpVectors(HighsLp& lp, const HighsInt num_new_col,
   lp.col_cost_.resize(new_num_col);
   lp.col_lower_.resize(new_num_col);
   lp.col_upper_.resize(new_num_col);
+  const bool have_integrality = (lp.integrality_.size() != 0);
+  if (have_integrality) {
+    assert(HighsInt(lp.integrality_.size()) == lp.num_col_);
+    lp.integrality_.resize(new_num_col);
+  }
   bool have_names = (lp.col_names_.size() != 0);
   if (have_names) lp.col_names_.resize(new_num_col);
   for (HighsInt new_col = 0; new_col < num_new_col; new_col++) {
@@ -1428,6 +1433,7 @@ void appendColsToLpVectors(HighsLp& lp, const HighsInt num_new_col,
     lp.col_upper_[iCol] = colUpper[new_col];
     // Cannot guarantee to create unique names, so name is blank
     if (have_names) lp.col_names_[iCol] = "";
+    if (have_integrality) lp.integrality_[iCol] = HighsVarType::kContinuous;
   }
 }
 
@@ -1647,9 +1653,12 @@ void changeLpIntegrality(HighsLp& lp,
   // technique
   HighsInt lp_col;
   HighsInt usr_col = -1;
-  // May be adding integrality to a pure LP for which lp.integrality_
-  // is of size 0.
-  lp.integrality_.resize(lp.num_col_);
+  // If changing integrality for a problem without an integrality
+  // vector (ie an LP), have to create it for the incumbent columns -
+  // which are naturally continuous
+  if (lp.integrality_.size() == 0)
+    lp.integrality_.assign(lp.num_col_, HighsVarType::kContinuous);
+  assert(HighsInt(lp.integrality_.size()) == lp.num_col_);
   for (HighsInt k = from_k; k < to_k + 1; k++) {
     if (interval || mask) {
       lp_col = k;