From 4cd506ab15c82ca32955eb96dfee6d006798e2ca Mon Sep 17 00:00:00 2001
From: Nuwan Yapa <yapanuwan@gmail.com>
Date: Wed, 21 Feb 2024 13:24:06 -0500
Subject: [PATCH] New basis ordering

---
 ho_basis.jl | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/ho_basis.jl b/ho_basis.jl
index 4a31c96..6a6a320 100644
--- a/ho_basis.jl
+++ b/ho_basis.jl
@@ -2,19 +2,47 @@
 gl(R, l, n) = throw("unimplemented")
 
 function get_sp_basis(E_max)
+    Es = Int[]
     ns = Int[]
     ls = Int[]
 
     # Heyde p67 with E = N and n = k + 1
-    for E in E_max:-1:0
-        for l in E:-2:0
-            n = 1 + (E - l) / 2
+    for E in 0 : E_max
+        for n in 0 : E ÷ 2
+            l = E - 2*n
+            push!(Es, E)
             push!(ns, n)
             push!(ls, l)
         end
     end
 
-    return (ns, ls)
+    return (Es, ns, ls)
+end
+
+function get_2p_basis(E_max)
+    Es = Int[]
+    n1s = Int[]
+    l1s = Int[]
+    n2s = Int[]
+    l2s = Int[]
+
+    # E = 2*n1 + l1 + 2*n2 + l2
+    for E in 0 : 2*E_max
+        for n1 in 0 : E ÷ 2
+            for n2 in 0 : (E - 2*n1) ÷ 2
+                for l1 in 0 : (E - 2*n1 - 2*n2)
+                    l2 = E - 2*n1 - 2*n2 - l1
+                    push!(Es, E)
+                    push!(n1s, n1)
+                    push!(l1s, l1)
+                    push!(n2s, n2)
+                    push!(l2s, l2)
+                end
+            end
+        end
+    end
+
+    return (Es, n1s, l1s, n2s, l2s)
 end
 
 get_V_matrix(V_l, ls, ns) = throw("unimplemented")