mat64: be strict with triangle for SymDense

mat64/matrix.go

@@ -522,20 +522,12 @@ func Max(a Matrix) float64 {
 		return max
 	case RawSymmetricer:
 		rm := m.RawSymmetric()
-		if rm.Uplo == blas.Upper {
-			max := math.Inf(-1)
-			for i := 0; i < rm.N; i++ {
-				for _, v := range rm.Data[i*rm.Stride+i : i*rm.Stride+rm.N] {
-					if v > max {
-						max = v
-					}
-				}
-			}
-			return max
+		if rm.Uplo != blas.Upper {
+			panic(badSymTriangle)
 		}
 		max := math.Inf(-1)
 		for i := 0; i < rm.N; i++ {
-			for _, v := range rm.Data[i*rm.Stride : i*rm.Stride+i+1] {
+			for _, v := range rm.Data[i*rm.Stride+i : i*rm.Stride+rm.N] {
 				if v > max {
 					max = v
 				}
@@ -604,20 +596,12 @@ func Min(a Matrix) float64 {
 		return min
 	case RawSymmetricer:
 		rm := m.RawSymmetric()
-		if rm.Uplo == blas.Upper {
-			min := math.Inf(1)
-			for i := 0; i < rm.N; i++ {
-				for _, v := range rm.Data[i*rm.Stride+i : i*rm.Stride+rm.N] {
-					if v < min {
-						min = v
-					}
-				}
-			}
-			return min
+		if rm.Uplo != blas.Upper {
+			panic(badSymTriangle)
 		}
 		min := math.Inf(1)
 		for i := 0; i < rm.N; i++ {
-			for _, v := range rm.Data[i*rm.Stride : i*rm.Stride+i+1] {
+			for _, v := range rm.Data[i*rm.Stride+i : i*rm.Stride+rm.N] {
 				if v < min {
 					min = v
 				}

mat64/symmetric.go

@@ -20,7 +20,8 @@ var (
 
 const badSymTriangle = "mat64: blas64.Symmetric not upper"
 
-// SymDense is a symmetric matrix that uses Dense storage.
+// SymDense is a symmetric matrix that uses dense storage. SymDense
+// matrices are encoded in upper the upper triangle.
 type SymDense struct {
 	mat blas64.Symmetric
 }
@@ -85,6 +86,17 @@ func (s *SymDense) RawSymmetric() blas64.Symmetric {
 	return s.mat
 }
 
+// SetRawSymmetric sets the underlying blas64.Symmertic used by the receiver.
+// Changes to elements in the receiver following the call will be reflected
+// in b. SetRawSymmetric will panic if b is not an upper-encoded symmetric
+// matrix.
+func (s *SymDense) SetRawSymmetric(b blas64.Symmetric) {
+	if b.Uplo != blas.Upper {
+		panic(badSymTriangle)
+	}
+	s.mat = b
+}
+
 func (s *SymDense) isZero() bool {
 	return s.mat.N == 0
 }