LA: fix IsConjugateSymmetric to ensure diagonal is real

src/Numerics/LinearAlgebra/Complex/DenseMatrix.cs

@@ -669,7 +669,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
                 }
                 return;
             }
-            
+
             base.DoMultiply(other, result);
         }
 
@@ -804,7 +804,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
                     denseResult.Values);
                 return;
             }
-            
+
             base.DoTransposeThisAndMultiply(rightSide, result);
         }
 
@@ -1263,6 +1263,15 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
                 return false;
             }
 
+            int stride = RowCount + 1;
+            for (var k = 0; k < _values.Length; k += stride)
+            {
+                if (!_values[k].IsReal())
+                {
+                    return false;
+                }
+            }
+
             for (var j = 0; j < ColumnCount; j++)
             {
                 var index = j * RowCount;

src/Numerics/LinearAlgebra/Complex/DiagonalMatrix.cs

@@ -1018,6 +1018,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
         /// </summary>
         public override sealed bool IsConjugateSymmetric()
         {
+            for (var k = 0; k < _data.Length; k ++)
+            {
+                if (!_data[k].IsReal())
+                {
+                    return false;
+                }
+            }
+
             return true;
         }
     }

src/Numerics/LinearAlgebra/Complex/Matrix.cs

@@ -671,6 +671,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
                 return false;
             }
 
+            for (var k = 0; k < RowCount; k++)
+            {
+                if (!At(k, k).IsReal())
+                {
+                    return false;
+                }
+            }
+
             for (var row = 0; row < RowCount; row++)
             {
                 for (var column = row + 1; column < ColumnCount; column++)

src/Numerics/LinearAlgebra/Complex32/DenseMatrix.cs

@@ -1260,6 +1260,15 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
                 return false;
             }
 
+            int stride = RowCount + 1;
+            for (var k = 0; k < _values.Length; k += stride)
+            {
+                if (!_values[k].IsReal())
+                {
+                    return false;
+                }
+            }
+
             for (var j = 0; j < ColumnCount; j++)
             {
                 var index = j * RowCount;

src/Numerics/LinearAlgebra/Complex32/DiagonalMatrix.cs

@@ -1012,6 +1012,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
         /// </summary>
         public override sealed bool IsConjugateSymmetric()
         {
+            for (var k = 0; k < _data.Length; k++)
+            {
+                if (!_data[k].IsReal())
+                {
+                    return false;
+                }
+            }
+
             return true;
         }
     }

src/Numerics/LinearAlgebra/Complex32/Matrix.cs

@@ -665,6 +665,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
                 return false;
             }
 
+            for (var k = 0; k < RowCount; k++)
+            {
+                if (!At(k, k).IsReal())
+                {
+                    return false;
+                }
+            }
+
             for (var row = 0; row < RowCount; row++)
             {
                 for (var column = row + 1; column < ColumnCount; column++)