Structural Transformation

Internal API

The functions documented on this page are internal implementation details of ModelingToolkit. They are not part of the public API and may change or be removed without notice in non-breaking releases. This documentation is provided to help contributors understand the codebase.

These functions are used for structural analysis and transformation of equation systems, including index reduction, tearing, and other algebraic manipulations used in the simplification process.

Tearing and Algebraic Simplification

ModelingToolkit.StructuralTransformations.tearing — Function

tearing(sys)

Tear the nonlinear equations in system. When simplify=true, we simplify the new residual equations after tearing. End users are encouraged to call mtkcompile instead, which calls this function internally.

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Missing docstring.

Missing docstring for tearing_reassemble. Check Documenter's build log for details.

Missing docstring.

Missing docstring for tearing_substitution. Check Documenter's build log for details.

Missing docstring.

Missing docstring for torn_system_jacobian_sparsity. Check Documenter's build log for details.

Missing docstring.

Missing docstring for find_solvables!. Check Documenter's build log for details.

Missing docstring.

Missing docstring for linear_subsys_adjmat!. Check Documenter's build log for details.

Index Reduction

ModelingToolkit.StructuralTransformations.dae_index_lowering — Function

dae_index_lowering(sys::System; kwargs...) -> System

Perform the Pantelides algorithm to transform a higher index DAE to an index 1 DAE. kwargs are forwarded to pantelides!. End users are encouraged to call mtkcompile instead, which calls this function internally.

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Missing docstring.

Missing docstring for pantelides!. Check Documenter's build log for details.

Missing docstring.

Missing docstring for pantelides_reassemble. Check Documenter's build log for details.

ModelingToolkit.StructuralTransformations.dummy_derivative — Function

dummy_derivative(sys)

Perform index reduction and use the dummy derivative technique to ensure that the system is balanced.

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Consistency Checking

Missing docstring.

Missing docstring for check_consistency. Check Documenter's build log for details.

Incidence Matrix Operations

ModelingToolkit.StructuralTransformations.sorted_incidence_matrix — Function

sorted_incidence_matrix(
    sys::ModelingToolkitBase.AbstractSystem
) -> Any

Obtain the incidence matrix of the system sorted by the SCCs. Requires that the system is simplified and has a schedule.

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Missing docstring.

Missing docstring for but_ordered_incidence. Check Documenter's build log for details.

Variable Ordering and Masks

Missing docstring.

Missing docstring for lowest_order_variable_mask. Check Documenter's build log for details.

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Missing docstring for highest_order_variable_mask. Check Documenter's build log for details.

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Missing docstring for computed_highest_diff_variables. Check Documenter's build log for details.

Shift Operations

These functions handle shift operations in discrete-time systems.

Missing docstring.

Missing docstring for shift2term. Check Documenter's build log for details.

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Missing docstring for lower_shift_varname. Check Documenter's build log for details.

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Missing docstring for simplify_shifts. Check Documenter's build log for details.

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Missing docstring for distribute_shift. Check Documenter's build log for details.

System Structure Types and Functions

Missing docstring.

Missing docstring for SystemStructure. Check Documenter's build log for details.

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Missing docstring for TearingState. Check Documenter's build log for details.

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Missing docstring for TransformationState. Check Documenter's build log for details.

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Missing docstring for isdiffvar. Check Documenter's build log for details.

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Missing docstring for isdervar. Check Documenter's build log for details.

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Missing docstring for isalgvar. Check Documenter's build log for details.

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Missing docstring for isdiffeq. Check Documenter's build log for details.

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Missing docstring for algeqs. Check Documenter's build log for details.

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Missing docstring for is_only_discrete. Check Documenter's build log for details.

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Missing docstring for dervars_range. Check Documenter's build log for details.

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Missing docstring for diffvars_range. Check Documenter's build log for details.

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Missing docstring for algvars_range. Check Documenter's build log for details.

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Missing docstring for get_fullvars. Check Documenter's build log for details.

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Missing docstring for system_subset. Check Documenter's build log for details.

Graph Types

Missing docstring.

Missing docstring for Matching. Check Documenter's build log for details.

Missing docstring.

Missing docstring for InducedCondensationGraph. Check Documenter's build log for details.

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Missing docstring for MatchedCondensationGraph. Check Documenter's build log for details.

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Missing docstring for Unassigned. Check Documenter's build log for details.

Missing docstring.

Missing docstring for unassigned. Check Documenter's build log for details.