spectral_galerkin_heat.core.property_expr
=========================================

.. py:module:: spectral_galerkin_heat.core.property_expr

.. autoapi-nested-parse::

   Whitelisted math expressions of ``T`` for temperature-dependent properties.

   A property branch (e.g. ``k.solid``) is given in config as either a bare
   number (a constant) or a string expression of ``T`` such as
   ``"9.248 + 0.01571 * T"`` or ``"12.41 * exp(-T / 3000.0)"``. :class:`PropertyExpr`
   parses that string once against a small node/name/function whitelist using
   Python's ``ast`` module. It never calls ``eval`` or ``exec`` on the expression
   itself, so there is no sandbox-escape surface. (A restricted-namespace ``eval``
   would be escapable through attribute access on any in-scope object.)

   The validated AST is then rendered to three targets, so the temperature-dependent
   hot path stays fully fused rather than falling back to a per-property Python
   callback:

   * :meth:`PropertyExpr.__call__`, a NumPy/CuPy-broadcasting evaluator that works
     on a scalar or a full field, on host or device;
   * :meth:`PropertyExpr.to_py_source`, a numba-``njit``-compatible Python source
     snippet using ``math.<fn>`` calls, which numba compiles natively, to build
     the fused CPU kernel;
   * :meth:`PropertyExpr.to_c_source`, a CUDA C expression, to build the fused GPU
     ``ElementwiseKernel``.

   Both source renderers take the target precision, since the literals they emit
   are what fixes the precision of the generated kernel.



Classes
-------

.. autoapisummary::

   spectral_galerkin_heat.core.property_expr.PropertyExpr


Module Contents
---------------

.. py:class:: PropertyExpr(expr)

   A validated math expression of ``T`` (or a bare constant).

   ``str(expr)`` must either parse as a plain number (a constant) or as an
   expression using ``T``, ``+ - * / **``, the constants ``pi``/``e``, and
   calls to a fixed whitelist of math functions (``sqrt``, ``exp``, ``log``,
   trig/hyperbolic functions, and so on). Anything else raises ``ValueError``
   at construction time: attribute access, subscripts, comprehensions, and
   unknown names or functions.


   .. py:method:: to_py_source(dtype=np.float32)

      Return numba-``njit``-compatible Python source with ``T`` free.

      :param dtype: Precision of the emitted literals, ``numpy.float32`` (default) or
                    ``numpy.float64``.
      :type dtype: data-type, optional



   .. py:method:: to_c_source(dtype=np.float32)

      Return a CUDA C expression with ``T`` free.

      :param dtype: Precision of the emitted literals and intrinsics,
                    ``numpy.float32`` (default) or ``numpy.float64``.
      :type dtype: data-type, optional