Function common_inds 

pub fn common_inds<I: IndexLike>(indices_a: &[I], indices_b: &[I]) -> Vec<I>

Find common indices between two index collections.

Returns a vector of indices that appear in both indices_a and indices_b (set intersection). This is similar to ITensors.jl’s commoninds function.

Time complexity: O(n + m) where n = len(indices_a), m = len(indices_b).

Arguments

• indices_a - First collection of indices
• indices_b - Second collection of indices

Returns

A vector containing indices that are common to both collections (matched by ID).

Example

use tensor4all_core::index::{DefaultIndex as Index, DynId};
use tensor4all_core::index_ops::common_inds;

let i = Index::new_dyn(2);
let j = Index::new_dyn(3);
let k = Index::new_dyn(4);

let indices_a = vec![i.clone(), j.clone()];
let indices_b = vec![j.clone(), k.clone()];

let common = common_inds(&indices_a, &indices_b);
assert_eq!(common.len(), 1);
assert_eq!(common[0].id, j.id);