// SubVec subtracts the vector b from a, placing the result in the receiver.
func (v *Vector) SubVec(a, b *Vector) {
ar := a.Len()
br := b.Len()
if ar != br {
panic(matrix.ErrShape)
}
v.reuseAs(ar)
if v.mat.Inc == 1 && a.mat.Inc == 1 && b.mat.Inc == 1 {
// Fast path for a common case.
asm.DaxpyUnitaryTo(v.mat.Data, -1, b.mat.Data, a.mat.Data)
return
}
asm.DaxpyIncTo(v.mat.Data, uintptr(v.mat.Inc), 0,
-1, b.mat.Data, a.mat.Data,
uintptr(ar), uintptr(b.mat.Inc), uintptr(a.mat.Inc), 0, 0)
}
// AddScaledVec adds the vectors a and alpha*b, placing the result in the receiver.
func (v *Vector) AddScaledVec(a *Vector, alpha float64, b *Vector) {
if alpha == 1 {
v.AddVec(a, b)
return
}
if alpha == -1 {
v.SubVec(a, b)
return
}
ar := a.Len()
br := b.Len()
if ar != br {
panic(matrix.ErrShape)
}
v.reuseAs(ar)
switch {
case alpha == 0: // v <- a
v.CopyVec(a)
case v == a && v == b: // v <- v + alpha * v = (alpha + 1) * v
blas64.Scal(ar, alpha+1, v.mat)
case v == a && v != b: // v <- v + alpha * b
if v.mat.Inc == 1 && b.mat.Inc == 1 {
// Fast path for a common case.
asm.DaxpyUnitaryTo(v.mat.Data, alpha, b.mat.Data, a.mat.Data)
} else {
asm.DaxpyInc(alpha, b.mat.Data, v.mat.Data,
uintptr(ar), uintptr(b.mat.Inc), uintptr(v.mat.Inc), 0, 0)
}
default: // v <- a + alpha * b or v <- a + alpha * v
if v.mat.Inc == 1 && a.mat.Inc == 1 && b.mat.Inc == 1 {
// Fast path for a common case.
asm.DaxpyUnitaryTo(v.mat.Data, alpha, b.mat.Data, a.mat.Data)
} else {
asm.DaxpyIncTo(v.mat.Data, uintptr(v.mat.Inc), 0,
alpha, b.mat.Data, a.mat.Data,
uintptr(ar), uintptr(b.mat.Inc), uintptr(a.mat.Inc), 0, 0)
}
}
}
