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use num_traits::Zero;
use ndarray::*;
use super::error::*;
use super::layout::*;
use lapack_traits::LapackScalar;
pub trait QR<Q, R> {
fn qr(self) -> Result<(Q, R)>;
}
impl<A, S, Sq, Sr> QR<ArrayBase<Sq, Ix2>, ArrayBase<Sr, Ix2>> for ArrayBase<S, Ix2>
where A: LapackScalar + Copy + Zero,
S: DataMut<Elem = A>,
Sq: DataOwned<Elem = A> + DataMut,
Sr: DataOwned<Elem = A> + DataMut
{
fn qr(mut self) -> Result<(ArrayBase<Sq, Ix2>, ArrayBase<Sr, Ix2>)> {
(&mut self).qr()
}
}
fn take_slice<A, S1, S2>(a: &ArrayBase<S1, Ix2>, n: usize, m: usize) -> ArrayBase<S2, Ix2>
where A: Copy,
S1: Data<Elem = A>,
S2: DataMut<Elem = A> + DataOwned
{
let av = a.slice(s![..n as isize, ..m as isize]);
let mut a = unsafe { ArrayBase::uninitialized((n, m)) };
a.assign(&av);
a
}
fn take_slice_upper<A, S1, S2>(a: &ArrayBase<S1, Ix2>, n: usize, m: usize) -> ArrayBase<S2, Ix2>
where A: Copy + Zero,
S1: Data<Elem = A>,
S2: DataMut<Elem = A> + DataOwned
{
let av = a.slice(s![..n as isize, ..m as isize]);
let mut a = unsafe { ArrayBase::uninitialized((n, m)) };
for ((i, j), val) in a.indexed_iter_mut() {
*val = if i <= j { av[(i, j)] } else { A::zero() };
}
a
}
impl<'a, A, S, Sq, Sr> QR<ArrayBase<Sq, Ix2>, ArrayBase<Sr, Ix2>> for &'a mut ArrayBase<S, Ix2>
where A: LapackScalar + Copy + Zero,
S: DataMut<Elem = A>,
Sq: DataOwned<Elem = A> + DataMut,
Sr: DataOwned<Elem = A> + DataMut
{
fn qr(mut self) -> Result<(ArrayBase<Sq, Ix2>, ArrayBase<Sr, Ix2>)> {
let n = self.rows();
let m = self.cols();
let k = ::std::cmp::min(n, m);
let l = self.layout()?;
let r = A::qr(l, self.as_allocated_mut()?)?;
let r: Array2<_> = reconstruct(l, r)?;
let q = self;
Ok((take_slice(q, n, k), take_slice_upper(&r, k, m)))
}
}
impl<'a, A, S, Sq, Sr> QR<ArrayBase<Sq, Ix2>, ArrayBase<Sr, Ix2>> for &'a ArrayBase<S, Ix2>
where A: LapackScalar + Copy + Zero,
S: Data<Elem = A>,
Sq: DataOwned<Elem = A> + DataMut,
Sr: DataOwned<Elem = A> + DataMut
{
fn qr(self) -> Result<(ArrayBase<Sq, Ix2>, ArrayBase<Sr, Ix2>)> {
let n = self.rows();
let m = self.cols();
let k = ::std::cmp::min(n, m);
let l = self.layout()?;
let mut q = self.to_owned();
let r = A::qr(l, q.as_allocated_mut()?)?;
let r: Array2<_> = reconstruct(l, r)?;
Ok((take_slice(&q, n, k), take_slice_upper(&r, k, m)))
}
}