Equation Class

class Equation(equation, context)

Purpose

Equation parses an expression once and exposes repeatable decimal-based evaluation.

Example

from decimal import Context
from piethorn.math.equation import Equation

equation = Equation("$value$ + $fallback:2$", Context())
equation.calculate({"value": 3})

Methods

has_variables()

Return whether the parsed equation contains variables.

Equation("1 + 2", Context()).has_variables()
Equation("$value$ + 2", Context()).has_variables()

calculate(variables=None)

Evaluate the expression with optional variable values.

Equation("1 + 2 * 3", Context()).calculate()
Equation("$value$ + 1", Context()).calculate({"value": 4})

Behavior notes

Equations without variables cache their computed value after the first evaluation.

Variables use decimal conversion through decimal.Decimal, and missing required variables raise ValueError.