Added options write_presolved_model_to_file and write_presolved_model…

…_file, and writes out OK unless file name is empty

app/RunHighs.cpp

@@ -62,6 +62,24 @@ int main(int argc, char** argv) {
       return (int)read_solution_status;
     }
   }
+  if (options.write_presolved_model_to_file) {
+    // Run presolve and write the presolved model to a file
+    HighsStatus status = highs.presolve();
+    if (status == HighsStatus::kError) return int(status);
+    HighsPresolveStatus model_presolve_status = highs.getModelPresolveStatus();
+    const bool ok_to_write =
+        model_presolve_status == HighsPresolveStatus::kNotReduced ||
+        model_presolve_status == HighsPresolveStatus::kReduced ||
+        model_presolve_status == HighsPresolveStatus::kReducedToEmpty ||
+        model_presolve_status == HighsPresolveStatus::kTimeout;
+    if (!ok_to_write) {
+      highsLogUser(log_options, HighsLogType::kInfo,
+                   "No presolved model to write to file\n");
+      return int(status);
+    }
+    status = highs.writePresolvedModel(options.write_presolved_model_file);
+    return int(status);
+  }
   // Solve the model
   HighsStatus run_status = highs.run();
   if (run_status == HighsStatus::kError) return int(run_status);

src/lp_data/HighsOptions.h

@@ -276,6 +276,7 @@ const string kSolutionFileString = "solution_file";
 const string kRangingString = "ranging";
 const string kVersionString = "version";
 const string kWriteModelFileString = "write_model_file";
+const string kWritePresolvedModelFileString = "write_presolved_model_file";
 const string kReadSolutionFileString = "read_solution_file";
 
 // String for HiGHS log file option
@@ -320,9 +321,11 @@ struct HighsOptionsStruct {
 
   std::string log_file;
   bool write_model_to_file;
+  bool write_presolved_model_to_file;
   bool write_solution_to_file;
   HighsInt write_solution_style;
   HighsInt glpsol_cost_row_location;
+  std::string write_presolved_model_file;
 
   // Control of HiGHS log
   bool output_flag;
@@ -434,6 +437,7 @@ struct HighsOptionsStruct {
         time_limit(0.0),
         solution_file(""),
         write_model_file(""),
+        write_presolved_model_file(""),
         random_seed(0),
         ranging(""),
         infinite_cost(0.0),
@@ -461,6 +465,7 @@ struct HighsOptionsStruct {
         simplex_max_concurrency(0),
         log_file(""),
         write_model_to_file(false),
+        write_presolved_model_to_file(false),
         write_solution_to_file(false),
         write_solution_style(0),
         glpsol_cost_row_location(0),
@@ -898,6 +903,16 @@ class HighsOptions : public HighsOptionsStruct {
                              advanced, &write_model_to_file, false);
     records.push_back(record_bool);
 
+    record_string = new OptionRecordString(
+        kWritePresolvedModelFileString, "Write presolved model file", advanced,
+        &write_presolved_model_file, kHighsFilenameDefault);
+    records.push_back(record_string);
+
+    record_bool = new OptionRecordBool(
+        "write_presolved_model_to_file", "Write the presolved model to a file",
+        advanced, &write_presolved_model_to_file, false);
+    records.push_back(record_bool);
+
     record_bool = new OptionRecordBool(
         "mip_detect_symmetry", "Whether MIP symmetry should be detected",
         advanced, &mip_detect_symmetry, true);