Confirm that frozen entries are frozen exactly

app-proto/src/engine.rs

@@ -414,6 +414,40 @@ mod tests {
         }
     }
     
+    // at the frozen indices, the optimization steps should have exact zeros,
+    // and the realized configuration should match the initial guess
+    #[test]
+    fn frozen_entry_test() {
+        let gram = {
+            let mut gram_to_be = PartialMatrix::new();
+            for j in 0..2 {
+                for k in j..2 {
+                    gram_to_be.push_sym(j, k, if (j, k) == (1, 1) { 1.0 } else { 0.0 });
+                }
+            }
+            gram_to_be
+        };
+        let guess = DMatrix::from_columns(&[
+            point(0.0, 0.0, 2.0),
+            sphere(0.0, 0.0, 0.0, 1.0)
+        ]);
+        let frozen = [(3, 0), (3, 1)];
+        println!();
+        let (config, success, history) = realize_gram(
+            &gram, guess.clone(), &frozen,
+            1.0e-12, 0.5, 0.9, 1.1, 200, 110
+        );
+        assert_eq!(success, true);
+        for base_step in history.base_step.into_iter() {
+            for index in frozen {
+                assert_eq!(base_step[index], 0.0);
+            }
+        }
+        for index in frozen {
+            assert_eq!(config[index], guess[index]);
+        }
+    }
+    
     // --- process inspection examples ---
     
     // these tests are meant for human inspection, not automated use. run them