.. index:: pair: class; rgpot::ExprPot
.. _doxid-classrgpot_1_1_expr_pot:

class rgpot::ExprPot
====================

.. toctree::
	:hidden:

	struct_rgpot_ExprPot_Impl.rst

Overview
~~~~~~~~

Energy :math:`E = f(E_0, E_1, \ldots)` over named child potentials. :ref:`More...<details-classrgpot_1_1_expr_pot>`


.. ref-code-block:: cpp
	:class: doxyrest-overview-code-block

	#include <ExprPot.hpp>
	
	class ExprPot: public rgpot::Potential< ExprPot > {
	public:
		// typedefs
	
		typedef std::pair<std::string, std::unique_ptr<:ref:`PotentialBase<doxid-classrgpot_1_1_potential_base>`>> :target:`Term<doxid-classrgpot_1_1_expr_pot_1a1caec6861ef78510e0911e70fbd78fdd>`;

		// structs
	
		struct :ref:`Impl<doxid-structrgpot_1_1_expr_pot_1_1_impl>`;

		// construction
	
		:target:`ExprPot<doxid-classrgpot_1_1_expr_pot_1a7abf6307d6a546808664de271bb9c3f0>`(std::string expression, std::vector<Term> terms);
		:target:`ExprPot<doxid-classrgpot_1_1_expr_pot_1a9590cc39b62ef66c2059b72c52543f01>`(const ExprPot&);
		:target:`ExprPot<doxid-classrgpot_1_1_expr_pot_1ada686b33e2e6861d82fba5e59ff512c9>`(ExprPot&& other);
		:target:`~ExprPot<doxid-classrgpot_1_1_expr_pot_1a5ae912d3ba3f09ee102d1839a2a821f9>`();

		// methods
	
		ExprPot& :target:`operator=<doxid-classrgpot_1_1_expr_pot_1afe939227b697cebfcd1320cc2ef550b0>`(const ExprPot&);
		ExprPot& :target:`operator=<doxid-classrgpot_1_1_expr_pot_1acc473f354141d96695ce5565eda61b1f>`(ExprPot&& other);
		void :target:`forceImpl<doxid-classrgpot_1_1_expr_pot_1a63c18bc88d2beb11a5cebbd81c1647b9>`(const :ref:`ForceInput<doxid-structrgpot_1_1_force_input>`& in, :ref:`ForceOut<doxid-structrgpot_1_1_force_out>`* out) const;
		virtual :ref:`PotCaps<doxid-structrgpot_1_1_pot_caps>` :ref:`caps<doxid-classrgpot_1_1_expr_pot_1acb09d0d256feb5f20d022a3a937d94ed>`() const;
		virtual uint64_t :ref:`paramsKey<doxid-classrgpot_1_1_expr_pot_1a5dd55c06126fb36c9cd539a84c162e9b>`() const;
		const std::string& :target:`expression<doxid-classrgpot_1_1_expr_pot_1a93ddae276c4f5d8a1072a75a66168903>`() const;
		double :ref:`dEnergyDTerm<doxid-classrgpot_1_1_expr_pot_1a37681cf4eb0cb3b65be9ba401151f759>`(const std::string& name) const;
	};
.. _details-classrgpot_1_1_expr_pot:

Detailed Documentation
~~~~~~~~~~~~~~~~~~~~~~

Energy :math:`E = f(E_0, E_1, \ldots)` over named child potentials.

The constructor parses ``expression`` with ``Lepton::Parser::parse``, compiles the energy once, and compiles ``ParsedExpression::differentiate(name)`` once per term. Unknown, duplicate, unused, or non-identifier names fail closed before any force call. Forces are the chain rule :math:`F = \sum_i (\partial f/\partial E_i)\, F_i`.

Methods
-------

.. index:: pair: function; caps
.. _doxid-classrgpot_1_1_expr_pot_1acb09d0d256feb5f20d022a3a937d94ed:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	virtual :ref:`PotCaps<doxid-structrgpot_1_1_pot_caps>` caps() const

Concurrency and evaluation capabilities of this potential.

Multi-threaded callers (NEB images, dimer endpoints) derive their sharing and cloning policy from this instead of hard-coded lists.

.. index:: pair: function; paramsKey
.. _doxid-classrgpot_1_1_expr_pot_1a5dd55c06126fb36c9cd539a84c162e9b:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	virtual uint64_t paramsKey() const

Fingerprint of the potential's parameter set.

Mixed into the result-cache key so results never cross parameter sets. Implementations hash their config field by field (see :ref:`ParamHash.hpp <doxid-_param_hash_8hpp_source>`) plus a kernel-version salt that changes whenever the numerics change. The default (0) suits parameter-free potentials whose numerics never changed.

.. index:: pair: function; dEnergyDTerm
.. _doxid-classrgpot_1_1_expr_pot_1a37681cf4eb0cb3b65be9ba401151f759:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	double dEnergyDTerm(const std::string& name) const

Analytic :math:`\partial f/\partial E_{\mathrm{name}}` from the construct-time compiled derivative, evaluated at the last child energies (zero if no force call has run).