Symbolic constraints

Symbols

symbol(name, unit=..., quantity_kind=...) creates a typed symbolic variable. Expressions built from symbols, quantities, and units form trees you can inspect and evaluate.

Equations and inequalities

• == between expressions yields an Equation.

• Comparisons yield strict or non-strict inequality nodes.

• Combine constraints with & (conjunction), | (disjunction), and ~ (negation).

Constraints are not plain Python bool; they evaluate only when you call .evaluate(...).

free_symbols

Expressions and constraints expose free_symbols for dependency analysis—useful when wiring executable models or solvers.

Evaluation

Pass a mapping from symbols to Quantity values. Optional tolerance arguments control numeric comparison for constraints.

Numeric compilation

unitflow.expr.compile.compile_numeric and compile_residual lower expression trees to plain Python callables over floats, with units baked in at compile time—suited for tight loops inside optimizers or root finders.

API: unitflow.expr.