Harmonise View signature with the rest of the API

mat64/dense.go

@@ -174,7 +174,8 @@ func (m *Dense) rowView(r int) []float64 {
 }
 
 // View returns a view on the receiver.
-func (m *Dense) View(i, j, r, c int) {
+func (m *Dense) View(a Matrix, i, j, r, c int) {
+	*m = *a.(*Dense)
 	m.mat.Data = m.mat.Data[i*m.mat.Stride+j : (i+r-1)*m.mat.Stride+(j+c)]
 	m.mat.Rows = r
 	m.mat.Cols = c
@@ -182,9 +183,8 @@ func (m *Dense) View(i, j, r, c int) {
 
 func (m *Dense) Submatrix(a Matrix, i, j, r, c int) {
 	// This is probably a bad idea, but for the moment, we do it.
-	v := *m
-	v.View(i, j, r, c)
-	m.Clone(&Dense{v.RawMatrix()})
+	m.View(a, i, j, r, c)
+	m.Clone(m)
 }
 
 func (m *Dense) Clone(a Matrix) {
@@ -883,8 +883,8 @@ func (m *Dense) Stack(a, b Matrix) {
 	}
 
 	m.Copy(a)
-	w := *m
-	w.View(ar, 0, br, bc)
+	var w Dense
+	w.View(m, ar, 0, br, bc)
 	w.Copy(b)
 }
 
@@ -908,8 +908,8 @@ func (m *Dense) Augment(a, b Matrix) {
 	}
 
 	m.Copy(a)
-	w := *m
-	w.View(0, ac, br, bc)
+	var w Dense
+	w.View(m, 0, ac, br, bc)
 	w.Copy(b)
 }
 

mat64/lq.go

@@ -53,8 +53,7 @@ func LQ(a *Dense) LQFactor {
 
 				// Apply transformation to remaining columns.
 				if k < m-1 {
-					*a = lq
-					a.View(k+1, k, m-k-1, n-k)
+					a.View(&lq, k+1, k, m-k-1, n-k)
 					projs = projs[0 : m-k-1]
 					projs.Mul(a, &hh)
 
@@ -109,10 +108,10 @@ func (f LQFactor) applyQTo(x *Dense, trans bool) {
 
 	if trans {
 		for k := nh - 1; k >= 0; k-- {
-			sub := *x
 			hh := f.LQ.RowView(k)[k:]
 
-			sub.View(k, 0, m-k, n)
+			var sub Dense
+			sub.View(x, k, 0, m-k, n)
 
 			blasEngine.Dgemv(
 				blas.ColMajor, blas.NoTrans,
@@ -128,10 +127,10 @@ func (f LQFactor) applyQTo(x *Dense, trans bool) {
 		}
 	} else {
 		for k := 0; k < nh; k++ {
-			sub := *x
 			hh := f.LQ.RowView(k)[k:]
 
-			sub.View(k, 0, m-k, n)
+			var sub Dense
+			sub.View(x, k, 0, m-k, n)
 
 			blasEngine.Dgemv(
 				blas.ColMajor, blas.NoTrans,

mat64/lq_test.go

@@ -84,8 +84,8 @@ func (s *S) TestLQD(c *check.C) {
 		l := lq.L()
 
 		lt := NewDense(rows, cols, nil)
-		ltview := *lt
-		ltview.View(0, 0, cols, cols)
+		var ltview Dense
+		ltview.View(lt, 0, 0, cols, cols)
 		ltview.TCopy(l)
 		lq.applyQTo(lt, true)
 

mat64/matrix.go

@@ -88,13 +88,13 @@ type Copier interface {
 	Copy(a Matrix) (r, c int)
 }
 
-// A Viewer can extract a submatrix view of of the receiver, starting at row i, column j
+// A Viewer can extract a submatrix view of the Matrix parameter, starting at row i, column j
 // and extending r rows and c columns. If i or j are out of range, or r or c extend beyond
 // the bounds of the matrix View will panic with ErrIndexOutOfRange. View must retain the
 // receiver's reference to the original matrix such that changes in the elements of the
 // submatrix are reflected in the original and vice versa.
 type Viewer interface {
-	View(i, j, r, c int)
+	View(a Matrix, i, j, r, c int)
 }
 
 // A Submatrixer can extract a copy of submatrix from a into the receiver, starting at row i,

mat64/qr.go

@@ -182,7 +182,7 @@ func (f QRFactor) Solve(b *Dense) (x *Dense) {
 	}
 
 	x = b
-	x.View(0, 0, n, bn)
+	x.View(b, 0, 0, n, bn)
 
 	return x
 }