From 1d64d616093d777515e59faeaf8f0daccf58a781 Mon Sep 17 00:00:00 2001
From: Paul Jakob Schroeder <paulschroeder90@gmail.com>
Date: Mon, 20 Feb 2023 12:49:24 -0500
Subject: [PATCH] Remove special subdim=2 case from SymmetricEigen

---
 src/linalg/symmetric_eigen.rs | 44 ++---------------------------------
 1 file changed, 2 insertions(+), 42 deletions(-)

diff --git a/src/linalg/symmetric_eigen.rs b/src/linalg/symmetric_eigen.rs
index cb660ea96..df2a411e9 100644
--- a/src/linalg/symmetric_eigen.rs
+++ b/src/linalg/symmetric_eigen.rs
@@ -5,7 +5,7 @@ use approx::AbsDiffEq;
 use num::Zero;
 
 use crate::allocator::Allocator;
-use crate::base::{DefaultAllocator, Matrix2, OMatrix, OVector, SquareMatrix, Vector2};
+use crate::base::{DefaultAllocator, OMatrix, OVector, SquareMatrix, Vector2};
 use crate::dimension::{Dim, DimDiff, DimSub, U1};
 use crate::storage::Storage;
 use simba::scalar::ComplexField;
@@ -131,10 +131,7 @@ where
             Self::delimit_subproblem(&diag, &mut off_diag, dim - 1, eps.clone());
 
         while end != start {
-            let subdim = end - start + 1;
-
-            #[allow(clippy::comparison_chain)]
-            if subdim > 2 {
+            {
                 let m = end - 1;
                 let n = end;
 
@@ -191,43 +188,6 @@ where
                 {
                     end -= 1;
                 }
-            } else if subdim == 2 {
-                let m = Matrix2::new(
-                    diag[start].clone(),
-                    off_diag[start].clone().conjugate(),
-                    off_diag[start].clone(),
-                    diag[start + 1].clone(),
-                );
-                let eigvals = m.eigenvalues().unwrap();
-
-                // A = [ a c ]
-                //     [ c b ]
-                // v = [ v1; v2 ]
-                // (A-lI)v = 0
-                // (a-l1)v1 + c*v2 = 0
-                //
-                // let v1 = c
-                // (a-l1)c + c*v2 = 0
-                // (a-l1)c = -c*v2
-                // v2 = l1 - a
-                let basis = Vector2::new(
-                    off_diag[start].clone(),
-                    eigvals.x.clone() - diag[start].clone(),
-                );
-
-                diag[start] = eigvals[0].clone();
-                diag[start + 1] = eigvals[1].clone();
-
-                if let Some(ref mut q) = q_mat {
-                    if let Some((rot, _)) =
-                        GivensRotation::try_new(basis.x.clone(), basis.y.clone(), eps.clone())
-                    {
-                        let rot = GivensRotation::new_unchecked(rot.c(), T::from_real(rot.s()));
-                        rot.rotate_rows(&mut q.fixed_columns_mut::<2>(start));
-                    }
-                }
-
-                end -= 1;
             }
 
             // Re-delimit the subproblem in case some decoupling occurred.