// MulVec computes a * b. The result is stored into the receiver.
// MulVec panics if the number of columns in a does not equal the number of rows in b.
func (v *Vector) MulVec(a Matrix, b *Vector) {
r, c := a.Dims()
br := b.Len()
if c != br {
panic(ErrShape)
}
a, trans := untranspose(a)
ar, ac := a.Dims()
v.reuseAs(r)
var restore func()
if v == a {
v, restore = v.isolatedWorkspace(a.(*Vector))
defer restore()
} else if v == b {
v, restore = v.isolatedWorkspace(b)
defer restore()
}
switch a := a.(type) {
case *Vector:
if a.Len() == 1 {
// {1,1} x {1,n}
av := a.At(0, 0)
for i := 0; i < b.Len(); i++ {
v.mat.Data[i*v.mat.Inc] = av * b.mat.Data[i*b.mat.Inc]
}
return
}
if b.Len() == 1 {
// {1,n} x {1,1}
bv := b.At(0, 0)
for i := 0; i < a.Len(); i++ {
v.mat.Data[i*v.mat.Inc] = bv * a.mat.Data[i*a.mat.Inc]
}
return
}
// {n,1} x {1,n}
var sum float64
for i := 0; i < c; i++ {
sum += a.At(i, 0) * b.At(i, 0)
}
v.SetVec(0, sum)
return
case RawSymmetricer:
amat := a.RawSymmetric()
blas64.Symv(1, amat, b.mat, 0, v.mat)
case RawTriangular:
v.CopyVec(b)
amat := a.RawTriangular()
ta := blas.NoTrans
if trans {
ta = blas.Trans
}
blas64.Trmv(ta, amat, v.mat)
case RawMatrixer:
amat := a.RawMatrix()
t := blas.NoTrans
if trans {
t = blas.Trans
}
blas64.Gemv(t, 1, amat, b.mat, 0, v.mat)
case Vectorer:
if trans {
col := make([]float64, ar)
for c := 0; c < ac; c++ {
v.mat.Data[c*v.mat.Inc] = blas64.Dot(ar,
blas64.Vector{Inc: 1, Data: a.Col(col, c)},
b.mat,
)
}
} else {
row := make([]float64, ac)
for r := 0; r < ar; r++ {
v.mat.Data[r*v.mat.Inc] = blas64.Dot(ac,
blas64.Vector{Inc: 1, Data: a.Row(row, r)},
b.mat,
)
}
}
default:
if trans {
col := make([]float64, ar)
for c := 0; c < ac; c++ {
for i := range col {
col[i] = a.At(i, c)
}
var f float64
for i, e := range col {
f += e * b.mat.Data[i*b.mat.Inc]
}
v.mat.Data[c*v.mat.Inc] = f
}
} else {
row := make([]float64, ac)
for r := 0; r < ar; r++ {
for i := range row {
row[i] = a.At(r, i)
}
var f float64
for i, e := range row {
f += e * b.mat.Data[i*b.mat.Inc]
}
v.mat.Data[r*v.mat.Inc] = f
}
}
}
}
// MulVec computes a * b if trans == false and a^T * b if trans == true. The
// result is stored into the receiver. MulVec panics if the number of columns in
// a does not equal the number of rows in b.
func (v *Vector) MulVec(a Matrix, trans bool, b *Vector) {
ar, ac := a.Dims()
br := b.Len()
if trans {
if ar != br {
panic(ErrShape)
}
} else {
if ac != br {
panic(ErrShape)
}
}
var w Vector
if v != a && v != b {
w = *v
}
if w.n == 0 {
if trans {
w.mat.Data = use(w.mat.Data, ac)
} else {
w.mat.Data = use(w.mat.Data, ar)
}
w.mat.Inc = 1
w.n = ar
if trans {
w.n = ac
}
} else {
if trans {
if ac != w.n {
panic(ErrShape)
}
} else {
if ar != w.n {
panic(ErrShape)
}
}
}
switch a := a.(type) {
case RawSymmetricer:
amat := a.RawSymmetric()
blas64.Symv(1, amat, b.mat, 0, w.mat)
case RawTriangular:
w.CopyVec(b)
amat := a.RawTriangular()
ta := blas.NoTrans
if trans {
ta = blas.Trans
}
blas64.Trmv(ta, amat, w.mat)
case RawMatrixer:
amat := a.RawMatrix()
t := blas.NoTrans
if trans {
t = blas.Trans
}
blas64.Gemv(t, 1, amat, b.mat, 0, w.mat)
case Vectorer:
if trans {
col := make([]float64, ar)
for c := 0; c < ac; c++ {
w.mat.Data[c*w.mat.Inc] = blas64.Dot(ar,
blas64.Vector{Inc: 1, Data: a.Col(col, c)},
b.mat,
)
}
} else {
row := make([]float64, ac)
for r := 0; r < ar; r++ {
w.mat.Data[r*w.mat.Inc] = blas64.Dot(ac,
blas64.Vector{Inc: 1, Data: a.Row(row, r)},
b.mat,
)
}
}
default:
if trans {
col := make([]float64, ar)
for c := 0; c < ac; c++ {
for i := range col {
col[i] = a.At(i, c)
}
var f float64
for i, e := range col {
f += e * b.mat.Data[i*b.mat.Inc]
}
w.mat.Data[c*w.mat.Inc] = f
}
} else {
row := make([]float64, ac)
for r := 0; r < ar; r++ {
for i := range row {
row[i] = a.At(r, i)
}
var f float64
for i, e := range row {
f += e * b.mat.Data[i*b.mat.Inc]
}
w.mat.Data[r*w.mat.Inc] = f
}
}
}
*v = w
}