Add failing example circuit of an LC shunt

[nikosavola]

Hi @flaport,

I was trying to implement a one-port lc_shunt_component but I seem to get errors with Jax that I don't fully understand. Something to do with varying array size I think.

You may run the test here with:

uv run pytest -k "test_lc_shunt_component"

I tried without @jax.jit in the core RF models but then this fails at the point where the circuit is flattened (_flat_circuit), either in analyze_insts_fn or analyze_fn.

Do you know what might be the problem?

Traceback

src/tests/test_rf_models.py:166: in test_lc_shunt_component
    s = type(self).lc_shunt_component(
src/tests/test_rf_models.py:127: in lc_shunt_component
    circuit, _ = sax.circuit(
src/sax/circuits.py:165: in circuit
    current_models[model_name] = circuit = _flat_circuit(
src/sax/circuits.py:345: in _flat_circuit
    analyzed = analyze_fn(dummy_instances, connections, ports)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
src/sax/backends/klu.py:130: in analyze_circuit_klu
    CSi = jnp.broadcast_to(Ci[None, :], mask.shape)[mask]
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.venv/lib/python3.13/site-packages/jax/_src/numpy/array_methods.py:1141: in op
    return getattr(self.aval, f"_{name}")(self, *args)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.venv/lib/python3.13/site-packages/jax/_src/numpy/array_methods.py:678: in _getitem
    return indexing.rewriting_take(self, item)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.venv/lib/python3.13/site-packages/jax/_src/numpy/indexing.py:655: in rewriting_take
    treedef, static_idx, dynamic_idx = split_index_for_jit(idx, arr.shape)
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.venv/lib/python3.13/site-packages/jax/_src/numpy/indexing.py:755: in split_index_for_jit
    idx = _expand_bool_indices(idx, shape)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.venv/lib/python3.13/site-packages/jax/_src/numpy/indexing.py:1092: in _expand_bool_indices
    raise errors.NonConcreteBooleanIndexError(abstract_i)
E   jax.errors.NonConcreteBooleanIndexError: Array boolean indices must be concrete; got bool[27,10]
E
E   See https://docs.jax.dev/en/latest/errors.html#jax.errors.NonConcreteBooleanIndexError
E   --------------------
E   For simplicity, JAX has removed its internal frames from the traceback of the following exception. Set JAX_TRACEBACK_FILTERING
=off to include these.

[joamatab]

@flaport can you take a look at this ?

this prevents hierarchical circuits