mat: improve mat element shadowing detection

mat/dense.go

@@ -485,6 +485,7 @@ func (m *Dense) Copy(a Matrix) (r, c int) {
 			// Nothing to do.
 		}
 	default:
+		m.checkOverlapMatrix(aU)
 		for i := 0; i < r; i++ {
 			for j := 0; j < c; j++ {
 				m.set(i, j, a.At(i, j))

mat/dense_arithmetic.go

@@ -43,6 +43,8 @@ func (m *Dense) Add(a, b Matrix) {
 		}
 	}
 
+	m.checkOverlapMatrix(aU)
+	m.checkOverlapMatrix(bU)
 	var restore func()
 	if m == aU {
 		m, restore = m.isolatedWorkspace(aU)
@@ -90,6 +92,8 @@ func (m *Dense) Sub(a, b Matrix) {
 		}
 	}
 
+	m.checkOverlapMatrix(aU)
+	m.checkOverlapMatrix(bU)
 	var restore func()
 	if m == aU {
 		m, restore = m.isolatedWorkspace(aU)
@@ -138,6 +142,8 @@ func (m *Dense) MulElem(a, b Matrix) {
 		}
 	}
 
+	m.checkOverlapMatrix(aU)
+	m.checkOverlapMatrix(bU)
 	var restore func()
 	if m == aU {
 		m, restore = m.isolatedWorkspace(aU)
@@ -186,6 +192,8 @@ func (m *Dense) DivElem(a, b Matrix) {
 		}
 	}
 
+	m.checkOverlapMatrix(aU)
+	m.checkOverlapMatrix(bU)
 	var restore func()
 	if m == aU {
 		m, restore = m.isolatedWorkspace(aU)
@@ -429,6 +437,8 @@ func (m *Dense) Mul(a, b Matrix) {
 		}
 	}
 
+	m.checkOverlapMatrix(aU)
+	m.checkOverlapMatrix(bU)
 	row := getFloats(ac, false)
 	defer putFloats(row)
 	for r := 0; r < ar; r++ {
@@ -699,6 +709,7 @@ func (m *Dense) Scale(f float64, a Matrix) {
 		return
 	}
 
+	m.checkOverlapMatrix(a)
 	for r := 0; r < ar; r++ {
 		for c := 0; c < ac; c++ {
 			m.set(r, c, f*a.At(r, c))
@@ -738,6 +749,7 @@ func (m *Dense) Apply(fn func(i, j int, v float64) float64, a Matrix) {
 		return
 	}
 
+	m.checkOverlapMatrix(a)
 	for r := 0; r < ar; r++ {
 		for c := 0; c < ac; c++ {
 			m.set(r, c, fn(r, c, a.At(r, c)))
@@ -845,6 +857,7 @@ func (m *Dense) Outer(alpha float64, x, y Vector) {
 	if rv, ok := xU.(RawVectorer); ok {
 		xmat = rv.RawVector()
 		m.checkOverlap((&VecDense{mat: xmat, n: x.Len()}).asGeneral())
+
 	} else {
 		fast = false
 	}

mat/shadow.go

@@ -70,10 +70,46 @@ func (m *Dense) checkOverlap(a blas64.General) bool {
 	return checkOverlap(m.RawMatrix(), a)
 }
 
+func (m *Dense) checkOverlapMatrix(a Matrix) bool {
+	if m == a {
+		return false
+	}
+	var amat blas64.General
+	switch a := a.(type) {
+	default:
+		return false
+	case RawMatrixer:
+		amat = a.RawMatrix()
+	case RawSymmetricer:
+		amat = generalFromSymmetric(a.RawSymmetric())
+	case RawTriangular:
+		amat = generalFromTriangular(a.RawTriangular())
+	}
+	return m.checkOverlap(amat)
+}
+
 func (s *SymDense) checkOverlap(a blas64.General) bool {
 	return checkOverlap(generalFromSymmetric(s.RawSymmetric()), a)
 }
 
+func (s *SymDense) checkOverlapMatrix(a Matrix) bool {
+	if s == a {
+		return false
+	}
+	var amat blas64.General
+	switch a := a.(type) {
+	default:
+		return false
+	case RawMatrixer:
+		amat = a.RawMatrix()
+	case RawSymmetricer:
+		amat = generalFromSymmetric(a.RawSymmetric())
+	case RawTriangular:
+		amat = generalFromTriangular(a.RawTriangular())
+	}
+	return s.checkOverlap(amat)
+}
+
 // generalFromSymmetric returns a blas64.General with the backing
 // data and dimensions of a.
 func generalFromSymmetric(a blas64.Symmetric) blas64.General {
@@ -89,6 +125,24 @@ func (t *TriDense) checkOverlap(a blas64.General) bool {
 	return checkOverlap(generalFromTriangular(t.RawTriangular()), a)
 }
 
+func (t *TriDense) checkOverlapMatrix(a Matrix) bool {
+	if t == a {
+		return false
+	}
+	var amat blas64.General
+	switch a := a.(type) {
+	default:
+		return false
+	case RawMatrixer:
+		amat = a.RawMatrix()
+	case RawSymmetricer:
+		amat = generalFromSymmetric(a.RawSymmetric())
+	case RawTriangular:
+		amat = generalFromTriangular(a.RawTriangular())
+	}
+	return t.checkOverlap(amat)
+}
+
 // generalFromTriangular returns a blas64.General with the backing
 // data and dimensions of a.
 func generalFromTriangular(a blas64.Triangular) blas64.General {

mat/symmetric.go

@@ -201,6 +201,8 @@ func (s *SymDense) AddSym(a, b Symmetric) {
 		}
 	}
 
+	s.checkOverlapMatrix(a)
+	s.checkOverlapMatrix(b)
 	for i := 0; i < n; i++ {
 		stmp := s.mat.Data[i*s.mat.Stride : i*s.mat.Stride+n]
 		for j := i; j < n; j++ {

mat/triangular.go

@@ -346,9 +346,7 @@ func (t *TriDense) Copy(a Matrix) (r, c int) {
 // Note that matrix inversion is numerically unstable, and should generally be
 // avoided where possible, for example by using the Solve routines.
 func (t *TriDense) InverseTri(a Triangular) error {
-	if rt, ok := a.(RawTriangular); ok {
+	t.checkOverlapMatrix(a)
-		t.checkOverlap(generalFromTriangular(rt.RawTriangular()))
-	}
 	n, _ := a.Triangle()
 	t.reuseAs(a.Triangle())
 	t.Copy(a)
@@ -385,6 +383,8 @@ func (t *TriDense) MulTri(a, b Triangular) {
 
 	aU, _ := untransposeTri(a)
 	bU, _ := untransposeTri(b)
+	t.checkOverlapMatrix(bU)
+	t.checkOverlapMatrix(aU)
 	t.reuseAs(n, kind)
 	var restore func()
 	if t == aU {
@@ -430,6 +430,9 @@ func (t *TriDense) ScaleTri(f float64, a Triangular) {
 	switch a := a.(type) {
 	case RawTriangular:
 		amat := a.RawTriangular()
+		if t != a {
+			t.checkOverlap(generalFromTriangular(amat))
+		}
 		if kind == Upper {
 			for i := 0; i < n; i++ {
 				ts := t.mat.Data[i*t.mat.Stride+i : i*t.mat.Stride+n]
@@ -449,6 +452,7 @@ func (t *TriDense) ScaleTri(f float64, a Triangular) {
 		}
 		return
 	default:
+		t.checkOverlapMatrix(a)
 		isUpper := kind == Upper
 		for i := 0; i < n; i++ {
 			if isUpper {