Use Buffer.BlockCopy for array shift.

Author: wo80

CSparse.Tests/Double/SparseMatrixTest.cs

@@ -525,13 +525,18 @@ public void TestOfIndexed_Coo_InPlace()
 
             coo = new CoordinateStorage<double>(5, 10, 3);
 
-            coo.At(0, 0, 1.0);
-            coo.At(1, 1, 1.0);
             coo.At(4, 4, 1.0);
+            coo.At(1, 1, 1.0);
+            coo.At(0, 0, 1.0);
+            coo.At(4, 4, -1.0); // Results in one explicit zero entry.
 
             A = SparseMatrix.OfIndexed(coo, true);
 
             Assert.AreEqual(3, A.NonZerosCount);
+
+            A.DropZeros();
+
+            Assert.AreEqual(2, A.NonZerosCount);
         }
 
         [Test]

CSparse/Converter.cs

@@ -183,10 +183,7 @@ private static void ConvertInPlace<T>(int columns, int nz, T[] values, int[] row
             }
 
             // Fix column pointers.
-            for (i = columns - 1; i > 0; i--)
-            {
-                work[i] = work[i - 1];
-            }
+            Buffer.BlockCopy(work, 0, work, Constants.SizeOfInt, columns * Constants.SizeOfInt);
 
             work[0] = 0;
         }