Merge pull request #3039 from Carl-Hossler/patch-1

Implement setBasis and setLogicalBasis methods

Author: galabovaa

highs/interfaces/highs_csharp_api.cs

@@ -344,7 +344,13 @@ private static extern int Highs_passHessian(
     private static extern int Highs_getHessianNumNz(IntPtr highs);
 
     [DllImport(highslibname)]
-    private static extern int Highs_getBasis(IntPtr highs, int[] colstatus, int[] rowstatus);
+    private static extern int Highs_getBasis(IntPtr highs, int[] colstatus, int[] rowstatus);    
+
+    [DllImport(highslibname)]
+    private static extern int Highs_setBasis(IntPtr highs, int[] col_status, int[] row_status);
+
+    [DllImport(highslibname)]
+    private static extern int Highs_setLogicalBasis(IntPtr highs);
 
     [DllImport(highslibname)]
     private static extern double Highs_getObjectiveValue(IntPtr highs);
@@ -1022,6 +1028,18 @@ public HighsStatus setSolution(HighsSolution solution)
         return (HighsStatus)HighsLpSolver.Highs_setSolution(this.highs, solution.colvalue, solution.rowvalue, solution.coldual, solution.rowdual);
     }
 
+    public HighsStatus setBasis(HighsBasis basis)
+    {
+        int[] col_status = basis.colbasisstatus.Select(x => (int)x).ToArray();
+        int[] row_status = basis.rowbasisstatus.Select(x => (int)x).ToArray();
+        return (HighsStatus)HighsLpSolver.Highs_setBasis(this.highs, col_status, row_status);
+    }
+
+    public HighsStatus setLogicalBasis()
+    {
+        return (HighsStatus)HighsLpSolver.Highs_setLogicalBasis(this.highs);
+    }
+
     /// <summary>Set a partial primal solution by passing values for a set of variables</summary>
     /// <param name="valuesByIndex">A dictionary that maps variable indices to variable values</param>
     /// <remarks>The sparse solution set by this function has values for a subset of the model's variables.