// RankTwo performs a symmmetric rank-two update to the matrix a and stores
// the result in the receiver
// m = a + alpha * (x * y' + y * x')
func (s *SymDense) RankTwo(a Symmetric, alpha float64, x, y *Vector) {
n := s.mat.N
if x.Len() != n {
panic(matrix.ErrShape)
}
if y.Len() != n {
panic(matrix.ErrShape)
}
var w SymDense
if s == a {
w = *s
}
if w.isZero() {
w.mat = blas64.Symmetric{
N: n,
Stride: n,
Uplo: blas.Upper,
Data: use(w.mat.Data, n*n),
}
} else if n != w.mat.N {
panic(matrix.ErrShape)
}
if s != a {
w.CopySym(a)
}
blas64.Syr2(alpha, x.mat, y.mat, w.mat)
*s = w
return
}
// RankTwo performs a symmmetric rank-two update to the matrix a and stores
// the result in the receiver
// m = a + alpha * (x * y' + y * x')
func (s *SymDense) RankTwo(a Symmetric, alpha float64, x, y []float64) {
n := s.mat.N
var w SymDense
if s == a {
w = *s
}
if w.isZero() {
w.mat = blas64.Symmetric{
N: n,
Stride: n,
Uplo: blas.Upper,
Data: use(w.mat.Data, n*n),
}
} else if n != w.mat.N {
panic(ErrShape)
}
if s != a {
w.CopySym(a)
}
if len(x) != n {
panic(ErrShape)
}
if len(y) != n {
panic(ErrShape)
}
blas64.Syr2(alpha, blas64.Vector{Inc: 1, Data: x}, blas64.Vector{Inc: 1, Data: y}, w.mat)
*s = w
return
}
// RankTwo performs a symmmetric rank-two update to the matrix a and stores
// the result in the receiver
// m = a + alpha * (x * y' + y * x')
func (s *SymDense) RankTwo(a Symmetric, alpha float64, x, y *Vector) {
n := s.mat.N
if x.Len() != n {
panic(matrix.ErrShape)
}
if y.Len() != n {
panic(matrix.ErrShape)
}
var w SymDense
if s == a {
w = *s
}
w.reuseAs(n)
if s != a {
w.CopySym(a)
}
blas64.Syr2(alpha, x.mat, y.mat, w.mat)
*s = w
return
}
// RankTwo performs a symmmetric rank-two update to the matrix a and stores
// the result in the receiver
// m = a + alpha * (x * y' + y * x')
func (s *SymDense) RankTwo(a Symmetric, alpha float64, x, y *Vector) {
n := s.mat.N
if x.Len() != n {
panic(matrix.ErrShape)
}
if y.Len() != n {
panic(matrix.ErrShape)
}
var w SymDense
if s == a {
w = *s
}
w.reuseAs(n)
if s != a {
if rs, ok := a.(RawSymmetricer); ok {
s.checkOverlap(rs.RawSymmetric())
}
w.CopySym(a)
}
blas64.Syr2(alpha, x.mat, y.mat, w.mat)
*s = w
return
}