feat(deep_causality_tensor): Applied multiple lints, fixes, and code improvements.

Signed-off-by: Marvin Hansen <marvin.hansen@gmail.com>

Author: marvin-hansen

deep_causality_multivector/tests/types/multifield/algebra/mod.rs

@@ -361,11 +361,13 @@ fn test_inverse_product_is_identity() {
     let metric = Metric::from_signature(2, 0, 0);
     let num_blades = 4;
 
-    // Create field with scalar = 3
+    // Create field with a proper versor (unit vector e1)
+    // In Euclidean space, e1 is its own inverse: e1 * e1 = 1
     let mut mvs = Vec::with_capacity(8);
     for _ in 0..8 {
         let mut data = vec![0.0f32; num_blades];
-        data[0] = 3.0;
+        // Use unit vector e1 which is a versor (invertible)
+        data[1] = 1.0; // e1 component
         mvs.push(CausalMultiVector::unchecked(data, metric));
     }
 
@@ -381,9 +383,19 @@ fn test_inverse_product_is_identity() {
         let scalar = mv.data()[0];
         assert!(
             (scalar - 1.0).abs() < 1e-3,
-            "A * A^-1 should be 1, got {}",
+            "A * A^-1 scalar part should be 1, got {}",
             scalar
         );
+
+        // Check that other components are near zero
+        for (i, &val) in mv.data().iter().enumerate().skip(1) {
+            assert!(
+                val.abs() < 1e-3,
+                "Non-scalar part of identity should be zero at index {}, got {}",
+                i,
+                val
+            );
+        }
     }
 }
 

deep_causality_tensor/src/types/backend/mlx/mlx_backend_linear_algebra.rs

@@ -214,12 +214,11 @@ fn explicit_inverse_4x4(input: &mlx_rs::Array) -> Result<mlx_rs::Array, String>
     // 5. InvS = S^-1
     let (is0, is1, is2, is3) = inv_2x2(&s0, &s1, &s2, &s3);
 
-    // F22 = InvS
-    let zero_is = sub_(&is0, &is0);
-    // Use & refs for sub_blocks args (owned arrays)
-    let (n_is0, n_is1, n_is2, n_is3) = sub_blocks(
-        &zero_is, &zero_is, &zero_is, &zero_is, &is0, &is1, &is2, &is3,
-    );
+    // Negate InvS for use in other blocks
+    let n_is0 = mlx_rs::ops::negative(&is0).unwrap();
+    let n_is1 = mlx_rs::ops::negative(&is1).unwrap();
+    let n_is2 = mlx_rs::ops::negative(&is2).unwrap();
+    let n_is3 = mlx_rs::ops::negative(&is3).unwrap();
     // F21 = -InvS * T1.
     let (f21_0, f21_1, f21_2, f21_3) =
         mul_2x2(&n_is0, &n_is1, &n_is2, &n_is3, &t1_0, &t1_1, &t1_2, &t1_3);

deep_causality_tensor/src/types/backend/mlx/mlx_backend_tensor.rs

@@ -125,7 +125,12 @@ impl TensorBackend for MlxBackend {
     }
 
     fn strides<T>(tensor: &Self::Tensor<T>) -> Vec<usize> {
-        tensor.as_array().strides().to_vec()
+        tensor
+            .as_array()
+            .strides()
+            .iter()
+            .map(|&s| s as usize)
+            .collect()
     }
 
     fn get<T: Clone>(tensor: &Self::Tensor<T>, index: &[usize]) -> Option<T> {

deep_causality_tensor/src/types/cpu_tensor/ops/tensor_ein_sum/ein_sum_impl.rs

@@ -282,12 +282,14 @@ where
                         }
                     }
 
-                    // Get values and accumulate
-                    if let (Some(lhs_val), Some(rhs_val)) =
-                        (lhs.get(&lhs_index), rhs.get(&rhs_index))
-                    {
-                        sum = sum + *lhs_val * *rhs_val;
-                    }
+                    // Get values and accumulate - use expect to fail fast on invalid indices
+                    let lhs_val = lhs
+                        .get(&lhs_index)
+                        .expect("Internal error: lhs index out of bounds in contraction");
+                    let rhs_val = rhs
+                        .get(&rhs_index)
+                        .expect("Internal error: rhs index out of bounds in contraction");
+                    sum = sum + *lhs_val * *rhs_val;
                 }
 
                 // Store result