diff --git a/mat/dense_arithmetic.go b/mat/dense_arithmetic.go
index dd4526f6..5bbf1058 100644
--- a/mat/dense_arithmetic.go
+++ b/mat/dense_arithmetic.go
@@ -300,20 +300,21 @@ func (m *Dense) Mul(a, b Matrix) {
 	// temporary memory.
 	// C = A^T * B = (B^T * A)^T
 	// C^T = B^T * A.
-	if aUrm, ok := aU.(RawMatrixer); ok {
-		amat := aUrm.RawMatrix()
+	if aU, ok := aU.(RawMatrixer); ok {
+		amat := aU.RawMatrix()
 		if restore == nil {
 			m.checkOverlap(amat)
 		}
-		if bUrm, ok := bU.(RawMatrixer); ok {
-			bmat := bUrm.RawMatrix()
+		switch bU := bU.(type) {
+		case RawMatrixer:
+			bmat := bU.RawMatrix()
 			if restore == nil {
 				m.checkOverlap(bmat)
 			}
 			blas64.Gemm(aT, bT, 1, amat, bmat, 0, m.mat)
 			return
-		}
-		if bU, ok := bU.(RawSymmetricer); ok {
+
+		case RawSymmetricer:
 			bmat := bU.RawSymmetric()
 			if aTrans {
 				c := getWorkspace(ac, ar, false)
@@ -324,8 +325,8 @@ func (m *Dense) Mul(a, b Matrix) {
 			}
 			blas64.Symm(blas.Right, 1, bmat, amat, 0, m.mat)
 			return
-		}
-		if bU, ok := bU.(RawTriangular); ok {
+
+		case RawTriangular:
 			// Trmm updates in place, so copy aU first.
 			bmat := bU.RawTriangular()
 			if aTrans {
@@ -345,8 +346,8 @@ func (m *Dense) Mul(a, b Matrix) {
 			m.Copy(a)
 			blas64.Trmm(blas.Right, bT, 1, bmat, m.mat)
 			return
-		}
-		if bU, ok := bU.(*VecDense); ok {
+
+		case *VecDense:
 			m.checkOverlap(bU.asGeneral())
 			bvec := bU.RawVector()
 			if bTrans {
@@ -369,12 +370,13 @@ func (m *Dense) Mul(a, b Matrix) {
 			return
 		}
 	}
-	if bUrm, ok := bU.(RawMatrixer); ok {
-		bmat := bUrm.RawMatrix()
+	if bU, ok := bU.(RawMatrixer); ok {
+		bmat := bU.RawMatrix()
 		if restore == nil {
 			m.checkOverlap(bmat)
 		}
-		if aU, ok := aU.(RawSymmetricer); ok {
+		switch aU := aU.(type) {
+		case RawSymmetricer:
 			amat := aU.RawSymmetric()
 			if bTrans {
 				c := getWorkspace(bc, br, false)
@@ -385,8 +387,8 @@ func (m *Dense) Mul(a, b Matrix) {
 			}
 			blas64.Symm(blas.Left, 1, amat, bmat, 0, m.mat)
 			return
-		}
-		if aU, ok := aU.(RawTriangular); ok {
+
+		case RawTriangular:
 			// Trmm updates in place, so copy bU first.
 			amat := aU.RawTriangular()
 			if bTrans {
@@ -406,8 +408,8 @@ func (m *Dense) Mul(a, b Matrix) {
 			m.Copy(b)
 			blas64.Trmm(blas.Left, aT, 1, amat, m.mat)
 			return
-		}
-		if aU, ok := aU.(*VecDense); ok {
+
+		case *VecDense:
 			m.checkOverlap(aU.asGeneral())
 			avec := aU.RawVector()
 			if aTrans {