error_solver.solvers.ErrorSolver

class error_solver.solvers.ErrorSolver(equations, names={}, combos={}, tol=0.01)

A class for solving systems of equations for their propagation errors based on their equation strings.

Parameters:

equations : list

A list of equation strings or string convertible objects.

names : dict

A dictionary of variable name replacements.

combos : dict

A dictionary of equation combinations.

tol : float

The tolerance used for verifying that values satisfy equations.

Examples

# error_solver_ex1.py
from error_solver import ErrorSolver

# Define the equations
EQUATIONS = [
    'A = pi * r**2',
    'V = A * h'
]

# Solve the equations by some means and assemble the values in a dictionary
values = {
    'h': 12,
    'r': 5,
    'A': 78.54,
    'V': 942.48
}

# Define the known error tolerances
errors = {
    'h': 0.05,
    'r': 0.05
}

solver = ErrorSolver(EQUATIONS)
solver.solve(values, errors)
#           value      error  pct_error  is_calc
# var
# A     78.539816   1.570796   2.000000     True
# V    942.477796  22.776547   2.416667     True
# h     12.000000   0.050000   0.416667    False
# r      5.000000   0.050000   1.000000    False

Methods

check(self, values, errors[, combo])	Checks that the input parameters are correct to carry out a solution.
equation_vars(self[, combo])	Returns a set of all variables in the equations.
from_file(path, \*\*kwargs)	Creates a new object from a specified Error Solver file.
get_equations(self[, combo])	Returns a list of equations for the specified combination.
get_partials(self[, combo])	Returns a list of partial derivatives for the specified combination.
jacobian(self, values, errors[, combo])	Returns the Jacobian matrix for the system of equations.
python_str(self)	Returns a Python module string for the equations and partial derivatives assigned to the object.
set_equations(self, equations)	Parses the input equations to sympy expressions and sets them to the object.
set_partials(self)	Calculates the partial derivatives for the equations assigned to the object.
solve(self, values, errors[, const, combo, …])	Solves for the propagation errors of the system of equations and returns a Data Frame of the results.
used_vars(self, values, errors[, combo])	Returns a lists of (1) variables present in both the equations and input values dictionary and (2) variables present in both the equations and input errors dictionary.
write_python(self, path)	Writes a Python module with the equations and partial derivatives assigned to the object.