Generalize general_tensor_mul to arbitrary dimensions

Author: t7phy

Cargo.lock

@@ -11,7 +11,10 @@ use float_cmp::approx_eq;
 use itertools::izip;
 use itertools::Itertools;
 use ndarray::linalg;
-use ndarray::{s, Array1, Array2, Array3, ArrayD, ArrayView1, ArrayView4, Axis, Ix1, Ix2};
+use ndarray::{
+    s, Array1, Array2, Array3, ArrayD, ArrayView1, ArrayView4, ArrayViewD, ArrayViewMutD, Axis,
+    Ix1, Ix2,
+};
 use std::iter;
 
 /// This structure captures the information needed to create an evolution kernel operator (EKO) for
@@ -462,7 +465,7 @@ pub(crate) fn evolve_slice_with_many(
                                 .map(|ops| (fk_table, ops))
                         })
                 {
-                    general_tensor_mul(*factor, &array, &ops, fk_table);
+                    general_tensor_mul(*factor, array.view(), &ops, &mut fk_table.view_mut());
                 }
             }
         }
@@ -496,11 +499,12 @@ pub(crate) fn evolve_slice_with_many(
 
 fn general_tensor_mul(
     factor: f64,
-    array: &ArrayD<f64>,
+    array: ArrayViewD<f64>,
     ops: &[&Array2<f64>],
-    fk_table: &mut ArrayD<f64>,
+    fk_table: &mut ArrayViewMutD<f64>,
 ) {
     match array.shape().len() {
+        0 => unreachable!(),
         1 => {
             let array = array.view().into_dimensionality::<Ix1>().unwrap();
             let mut fk_table = fk_table.view_mut().into_dimensionality::<Ix1>().unwrap();
@@ -516,7 +520,17 @@ fn general_tensor_mul(
             // fk_table += factor * ops[0] * tmp
             linalg::general_mat_mul(factor, ops[0], &tmp, 1.0, &mut fk_table);
         }
-        // TODO: generalize this to n dimensions
-        _ => unimplemented!(),
+        _ => {
+            let (ops_0, ops_dm1) = ops.split_first().unwrap();
+
+            for (mut fk_table_i, ops_0_i) in fk_table
+                .axis_iter_mut(Axis(0))
+                .zip(ops_0.axis_iter(Axis(0)))
+            {
+                for (array_j, ops_0_ij) in array.axis_iter(Axis(0)).zip(ops_0_i.iter()) {
+                    general_tensor_mul(factor * ops_0_ij, array_j, &ops_dm1, &mut fk_table_i);
+                }
+            }
+        }
     }
 }