From 4afd51c2a04bd503d18ce87358be2623de1e515c Mon Sep 17 00:00:00 2001
From: Toshiki Teramura <toshiki.teramura@gmail.com>
Date: Wed, 28 Sep 2022 00:19:39 +0900
Subject: [PATCH] WIP: LeastSquaresWork

---
 lax/src/least_squares.rs | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/lax/src/least_squares.rs b/lax/src/least_squares.rs
index 532d1e6b..0af2f0b7 100644
--- a/lax/src/least_squares.rs
+++ b/lax/src/least_squares.rs
@@ -12,6 +12,14 @@ pub struct LeastSquaresOwned<A: Scalar> {
     pub rank: i32,
 }
 
+/// Result of LeastSquares
+pub struct LeastSquaresRef<'work, A: Scalar> {
+    /// singular values
+    pub singular_values: &'work [A::Real],
+    /// The rank of the input matrix A
+    pub rank: i32,
+}
+
 #[cfg_attr(doc, katexit::katexit)]
 /// Solve least square problem
 pub trait LeastSquaresSvdDivideConquer_: Scalar {
@@ -29,7 +37,18 @@ pub trait LeastSquaresSvdDivideConquer_: Scalar {
         a: &mut [Self],
         b_layout: MatrixLayout,
         b: &mut [Self],
-    ) -> Result<LeastSquaresOutput<Self>>;
+    ) -> Result<LeastSquaresOwned<Self>>;
+}
+
+pub struct LeastSquaresWork<T: Scalar> {
+    pub work: Vec<MaybeUninit<T>>,
+}
+
+pub trait LeastSquaresWorkImpl: Sized {
+    type Elem: Scalar;
+    fn new(a_layout: MatrixLayout, b_layout: MatrixLayout) -> Result<Self>;
+    fn calc(&mut self, a: &mut [Self], b: &mut [Self]) -> Result<LeastSquaresRef<Self::Elem>>;
+    fn eval(self, a: &mut [Self], b: &mut [Self]) -> Result<LeastSquaresOwned<Self::Elem>>;
 }
 
 macro_rules! impl_least_squares {