Function permute_indices_on_session 

pub fn permute_indices_on_session(
    session: &mut Session<'_>,
    tensor: &IdxTensor,
    new_indices: &[DynIndex],
) -> Result<IdxTensor, IdxTensorError>

Align a dense host tensor to a caller-supplied index order on a caller-held explicit session.

The numerical counterpart of IdxTensor::permute_indices, which the app crates use to align operands before a contraction. The index list must be a permutation of the tensor’s own indices by full index equality, exactly as the compatibility route requires; the permutation is derived with the same helper, so the two routes refuse the same inputs with the same messages. Execution is permute_on_session’s, so this route serves the same dense floating-dtype domain, and an identity permutation is metadata only - it returns the same storage under the supplied index list, for any representation, without touching the session.

Errors

Returns a typed IdxTensorError when the index list is not a permutation of the tensor’s indices (the compatibility helper’s reason, reported under this entry point’s operation name), when a supplied index carries a different dimension than the tensor’s matching index (this route’s own message), under the same conditions as a nonidentity permute_on_session refuses an operand - whose errors keep that route’s operation name, because the execution is delegated - and when the session rejects the permutation or the result cannot be published. A delegated storage error keeps its original source rather than being re-labelled.

Examples

use tensor4all_core::index::{DefaultIndex as Index, DynId};
use tensor4all_core::{permute_indices_on_session, IdxTensor};
use tensor4all_tensorbackend::CpuExecutionContext;
use tensor4all_tensorbackend::CpuBackend;

let context = CpuExecutionContext::from_backend(CpuBackend::with_threads(1)?);
let i = Index::new_dyn(2);
let k = Index::new_dyn(3);
let tensor: IdxTensor =
    IdxTensor::from_dense(vec![i.clone(), k.clone()], (1..=6).map(|v| v as f64).collect())?;

let aligned = context.with_concrete_session(|session| {
    permute_indices_on_session(session, &tensor, &[k.clone(), i.clone()])
})??;
assert_eq!(aligned.indices()[0], k);
assert_eq!(aligned.to_vec::<f64>()?, vec![1.0, 3.0, 5.0, 2.0, 4.0, 6.0]);