diff --git a/Basis/ERI.ml b/Basis/ERI.ml
index fab2f2e..cbd1807 100644
--- a/Basis/ERI.ml
+++ b/Basis/ERI.ml
@@ -262,13 +262,13 @@ let of_basis_parallel basis =
 
 
   let t0 = Unix.gettimeofday () in
-  let ishell = ref 0 in
+  let ishell = ref max_int in
 
   let input_stream = Stream.of_list (List.rev shell_pairs) in
 
   let f shell_p =
       let () = 
-        if Parallel.rank < 2 && Cs.index (Csp.shell_a shell_p) > !ishell then
+        if Parallel.rank < 2 && Cs.index (Csp.shell_a shell_p) < !ishell then
           (ishell := Cs.index (Csp.shell_a shell_p) ; print_int !ishell ; print_newline ())
       in
 
diff --git a/Utils/DIIS.mli b/Utils/DIIS.mli
index cfef058..9f1ce66 100644
--- a/Utils/DIIS.mli
+++ b/Utils/DIIS.mli
@@ -5,7 +5,7 @@ At iteration {% $m$ %}, one has:
 - {% $\mathbf{p}_m$ %}, a vector of parameters
 - {% $\mathbf{e}_m$ %}, an approximate error vector
 
-The DIIS approximate solution for iteration $m+1$ is given by
+The DIIS approximate solution for iteration {% $m+1$ %} is given by
 
 {% \begin{align*}
 \mathbf{p}_{m+1} & = \sum_{i=1}^m c_i (\mathbf{p}^f + \mathbf{e}_i) \\
diff --git a/Utils/FourIdxStorage.ml b/Utils/FourIdxStorage.ml
index 76532cc..d9a89aa 100644
--- a/Utils/FourIdxStorage.ml
+++ b/Utils/FourIdxStorage.ml
@@ -20,7 +20,7 @@ let key_of_indices ~r1 ~r2 =
   let f i k = 
     let p, r = 
       if i <= k then i, k else k, i
-    in p+ (r*r-r)/2
+    in p + (r*(r-1))/2
   in
   let p = f i k and q = f j l in
   f p q