mat: add VecDenseCopyOf function

mat/vector.go

@@ -21,6 +21,7 @@ var (
 // Vector is a column vector.
 type Vector interface {
 	Matrix
+	AtVec(int) float64
 	Len() int
 }
 
@@ -120,16 +121,29 @@ func (v *VecDense) Reset() {
 
 // CloneVec makes a copy of a into the receiver, overwriting the previous value
 // of the receiver.
-func (v *VecDense) CloneVec(a *VecDense) {
+func (v *VecDense) CloneVec(a Vector) {
 	if v == a {
 		return
 	}
-	v.n = a.n
+	v.n = a.Len()
 	v.mat = blas64.Vector{
 		Inc:  1,
 		Data: use(v.mat.Data, v.n),
 	}
-	blas64.Copy(v.n, a.mat, v.mat)
+	if r, ok := a.(RawVectorer); ok {
+		blas64.Copy(v.n, r.RawVector(), v.mat)
+		return
+	}
+	for i := 0; i < a.Len(); i++ {
+		v.SetVec(i, a.AtVec(i))
+	}
+}
+
+// VecDenseCopyOf returns a newly allocated copy of the elements of a.
+func VecDenseCopyOf(a Vector) *VecDense {
+	v := &VecDense{}
+	v.CloneVec(a)
+	return v
 }
 
 func (v *VecDense) RawVector() blas64.Vector {