Fix out of range bug by reverting buffer rewind improvement

Change-Id: I041621f072f895caffc638e551fc8280e5cb7e6f
diff --git a/matrix.go b/matrix.go
index a36dfbb..57f0c14 100644
--- a/matrix.go
+++ b/matrix.go
@@ -526,12 +526,10 @@
 				log.Println("-> Rewind buffer", bufft, buffc, buffi, epsilonOffset)
 			}
 
-			buffer = buffer[buffc:]
-			/*
-				for x, i := range buffer[buffc:buffi] {
-					buffer[x] = i
-				}
-			*/
+			// buffer = buffer[buffc:]
+			for x, i := range buffer[buffc:buffi] {
+				buffer[x] = i
+			}
 
 			buffi -= buffc
 			// epsilonOffset -= buffo