diff --git a/app-proto/src/engine.rs b/app-proto/src/engine.rs
index 967697f..421975c 100644
--- a/app-proto/src/engine.rs
+++ b/app-proto/src/engine.rs
@@ -340,36 +340,33 @@ mod tests {
     //
     #[test]
     fn irisawa_hexlet_test() {
-        let gram = PartialMatrix({
-            let mut entries = Vec::<MatrixEntry>::new();
+        let gram = {
+            let mut gram_to_be = PartialMatrix::new();
             for s in 0..9 {
                 // each sphere is represented by a spacelike vector
-                entries.push(MatrixEntry { index: (s, s), value: 1.0 });
+                gram_to_be.push_sym(s, s, 1.0);
                 
                 // the circumscribing sphere is tangent to all of the other
                 // spheres, with matching orientation
                 if s > 0 {
-                    entries.push(MatrixEntry { index: (0, s), value: 1.0 });
-                    entries.push(MatrixEntry { index: (s, 0), value: 1.0 });
+                    gram_to_be.push_sym(0, s, 1.0);
                 }
                 
                 if s > 2 {
                     // each chain sphere is tangent to the "sun" and "moon"
                     // spheres, with opposing orientation
                     for n in 1..3 {
-                        entries.push(MatrixEntry { index: (s, n), value: -1.0 });
-                        entries.push(MatrixEntry { index: (n, s), value: -1.0 });
+                        gram_to_be.push_sym(s, n, -1.0);
                     }
                     
                     // each chain sphere is tangent to the next chain sphere,
                     // with opposing orientation
                     let s_next = 3 + (s-2) % 6;
-                    entries.push(MatrixEntry { index: (s, s_next), value: -1.0 });
-                    entries.push(MatrixEntry { index: (s_next, s), value: -1.0 });
+                    gram_to_be.push_sym(s, s_next, -1.0);
                 }
             }
-            entries
-        });
+            gram_to_be
+        };
         let guess = DMatrix::from_columns(
             [
                 sphere(0.0, 0.0, 0.0, 15.0),