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//! solvers of BVPs and IVPs, optization, nonlinear algeraic systems and more
/// #########################ODEs SECTION######################
///
/// SOLVER OF STIFF IVPs (initial value problems)
/// direct rewrite to Rust python code from SciPy
///
/// Example#1
/// ```
///use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use RustedSciThe::symbolic::symbolic_functions::Jacobian;
/// use RustedSciThe::numerical::ODE_api::ODEsolver;
/// // set RHS of system as vector of strings
/// let RHS = vec!["-z-exp(-y)", "y"];
/// // parse RHS as symbolic expressions
/// let Equations = Expr::parse_vector_expression(RHS.clone());
/// let values = vec!["z".to_string(), "y".to_string()];
/// println!("Equations = {:?}", Equations);
/// // set argument
/// let arg = "x".to_string();
/// // set method
/// let method = "BDF".to_string();
/// // set initial conditions
/// let t0 = 0.0;
/// let y0 = vec![1.0, 1.0];
/// let t_bound = 1.0;
/// // set solver parameters (optional)
/// let first_step = None;
/// let atol = 1e-5;
/// let rtol = 1e-5;
/// let max_step = 1e-3;
/// let jac_sparsity = None;
/// let vectorized = false;
/// // create instance of ODE solver and solve the system
/// let mut ODE_instance = ODEsolver::new_complex(
/// Equations,
/// values,
/// arg,
/// method,
/// t0,
/// y0.into(),
/// t_bound,
/// max_step,
/// rtol,
/// atol,
/// jac_sparsity,
/// vectorized,
/// first_step,
/// );
///
/// ODE_instance.solve();
/// ODE_instance.plot_result();
/// ```
/// Backward Euler method (good for stiff ODEs)
///
/// Example#1
/// ```
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use RustedSciThe::numerical::BE::BE;
/// use nalgebra::DVector;
/// // Backward Euler method: slightly non-linear ODE
/// let RHS = vec!["-z-exp(-y)", "y"];
/// // parse RHS as symbolic expressions
/// let Equations = Expr::parse_vector_expression(RHS.clone());
/// let values = vec![ "z".to_string(), "y".to_string()];
/// println!("eq_system = {:?}", Equations);
/// let y0 = DVector::from_vec(vec![1.0, 1.0]);
/// let arg = "x".to_string();
/// let tolerance = 1e-2;
/// let max_iterations = 500;
/// let h = Some(1e-3);
/// let t0 = 0.0;
/// let t_bound = 1.0;
/// let mut solver = BE::new();
/// solver.set_initial( Equations, values, arg, tolerance, max_iterations, h, t0, t_bound, y0);
/// println!("y = {:?}, initial_guess = {:?}", solver.newton.y,solver.newton.initial_guess);
/// solver.newton.eq_generate();
/// solver.solve();
/// let result = solver.get_result();
/// // println!("\n result 0 = {:?}", result.0);
/// // println!("\n result 1 = {:?}", result.1);
/// // println!("result = {:?}", result.1.unwrap().shape());
/// solver.plot_result();
/// ```
/// Newton Raphson solver for Backward Euler method
/// Boundary value problems solvers for stiff nonlinear ODEs
///
/// solver NR_Damp_solver_frozen implements NR method with damping
/// but without adaptive grid.
/// Frozen jacobian strategy - recalculating jacobian on condition:
/// Description of strategy key of strategy value user must provude for strategy
/// 1. only first time: "Frozen_naive" None
/// 2. every m-th time, where m is a parameter of the strategy: "every_m" m
/// 3. every time when the solution norm greater than a certain threshold A: "at_high_norm". A
/// 4. when norm of (i-1) iter multiplied by certain value B(<1) is lower than norm of i-th iter : "at_low_speed". B
/// 5. complex - combined strategies 2,3,4 "complex" vec of parameters [m, A, B]
///
///
/// Example#1
/// ```
/// use nalgebra::DMatrix;
/// use nalgebra::DVector;
/// use std::collections::HashMap;
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use RustedSciThe::numerical::BVP_Damp::NR_Damp_solver_frozen::NRBVP;
/// let eq1 = Expr::parse_expression("y-z");
/// let eq2 = Expr::parse_expression("-z^2");
/// let eq_system = vec![eq1, eq2];
///
/// let values = vec!["z".to_string(), "y".to_string()];
/// let arg = "x".to_string();
/// let tolerance = 1e-5;
/// let max_iterations = 1500;
///
/// let t0 = 0.0;
/// let t_end = 1.0;
/// let n_steps = 100; // Dense: 200 -300ms, 400 - 2s, 800 - 22s, 1600 - 2 min,
/// let strategy = "Frozen".to_string();//
/// let strategy_params = Some(HashMap::from([("complex".to_string(),
/// Some(Vec::from( [2f64, 5.0, 1e-1, ] ))
/// )]));
/// //
/// // or
/// // Some(HashMap::from([("Frozen_naive".to_string(), None)]));
/// // or
/// // Some(HashMap::from([("every_m".to_string(),
/// // Some(Vec::from( [ 5 as f64] ))
/// // )]));
/// // or
/// // Some(HashMap::from([("at_high_morm".to_string(),
/// // Some(Vec::from( [ 5 as f64] ))
/// //)]));
/// //or
/// //Some(HashMap::from([("at_low_speed".to_string(),
/// // Some(Vec::from( [ 1e-2] ))
/// //)]));
/// //or
/// // Some(HashMap::from([("complex".to_string(),
/// // Some(Vec::from( [ 2.0, 5.0, 1e-, ] ))
/// //)]));
/// // */
/// let method = "Sparse".to_string();// or "Dense"
/// let linear_sys_method = None;
/// let ones = vec![0.0; values.len()*n_steps];
/// let initial_guess: DMatrix<f64> = DMatrix::from_column_slice(values.len(), n_steps, DVector::from_vec(ones).as_slice());
/// let mut BorderConditions = HashMap::new();
/// BorderConditions.insert("z".to_string(), vec![(0usize, 1.0f64)]);
/// BorderConditions.insert("y".to_string(), vec![(1usize, 1.0f64)]);
/// assert_eq!(&eq_system.len(), &2);
/// let mut nr = NRBVP::new(eq_system,
/// initial_guess,
/// values,
/// arg,
/// BorderConditions, t0, t_end, n_steps,strategy, strategy_params, linear_sys_method, method, tolerance, max_iterations);
/// println!("solving system");
/// #[allow(unused_variables)]
/// let solution = nr.solve().unwrap();
/// // println!("result = {:?}", solution);
/// nr.plot_result();
/// ```
///
/// NR_Damp_solver_damped solver implements
/// Modified Newton method or Damped Newton method with adaptive grid for solving Boundary value problems for systems of nonlinear ordinary differential equations.
///
/// The code mostly inspired by sources listed below:
/// Cantera MultiNewton solver (MultiNewton.cpp )
/// TWOPNT fortran solver (see "The Twopnt Program for Boundary Value Problems" by J. F. Grcar and Chemkin Theory Manual p.261)
///
/// Example#2
/// ```
/// use nalgebra::DMatrix;
/// use nalgebra::DVector;
/// use std::collections::HashMap;
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use RustedSciThe::numerical::BVP_Damp::NR_Damp_solver_damped::SolverParams;
/// use RustedSciThe::numerical::BVP_Damp::NR_Damp_solver_damped::NRBVP as NRBDVPd;
/// let eq1 = Expr::parse_expression("y-z");
/// let eq2 = Expr::parse_expression("-z^3");
/// let eq_system = vec![eq1, eq2];
/// let values = vec!["z".to_string(), "y".to_string()];
/// let arg = "x".to_string();
/// let tolerance = 1e-5;
/// let max_iterations = 20;
/// let t0 = 0.0;
/// let t_end = 1.0;
/// let n_steps = 50; // Dense: 200 -300ms, 400 - 2s, 800 - 22s, 1600 - 2 min,
/// let strategy = "Damped".to_string();//
/// let strategy_params = SolverParams::default();
/// let scheme = "forward".to_string();
/// let method = "Sparse".to_string();// or "Dense"
/// let linear_sys_method = None;
/// let ones = vec![0.0; values.len()*n_steps];
/// let initial_guess: DMatrix<f64> = DMatrix::from_column_slice(values.len(), n_steps, DVector::from_vec(ones).as_slice());
/// let mut BorderConditions = HashMap::new();
/// BorderConditions.insert("z".to_string(), vec![(0usize, 1.0f64)]);
/// BorderConditions.insert("y".to_string(), vec![(1usize, 1.0f64)]);
/// let Bounds = HashMap::from([ ("z".to_string(), (-10.0, 10.0), ), ("y".to_string(), (-7.0, 7.0), ) ]);
/// let rel_tolerance = HashMap::from([ ("z".to_string(), 1e-4 ), ("y".to_string(), 1e-4, ) ]);
/// assert_eq!(&eq_system.len(), &2);
/// let mut nr = NRBDVPd::new(eq_system,
/// initial_guess,
/// values,
/// arg,
/// BorderConditions, t0, t_end, n_steps,scheme, strategy, Some(strategy_params), linear_sys_method, method, tolerance, Some(rel_tolerance), max_iterations, Some(Bounds),None);
/// println!("solving system");
/// #[allow(unused_variables)]
/// let solution = nr.solve().unwrap();
/// // println!("result = {:?}", solution);
/// nr.plot_result();
/// ```
/// API for both solvers
/// Example#3
/// ```
/// use nalgebra::DMatrix;
/// use nalgebra::DVector;
/// use std::collections::HashMap;
/// use RustedSciThe::numerical::BVP_api::BVP;
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
/// let eq1 = Expr::parse_expression("y-z");
/// let eq2 = Expr::parse_expression("-z^3");
/// let eq_system = vec![eq1, eq2];
///
///
/// let values = vec!["z".to_string(), "y".to_string()];
/// let arg = "x".to_string();
/// let tolerance = 1e-5;
/// let max_iterations = 20;
///
/// let t0 = 0.0;
/// let t_end = 1.0;
/// let n_steps = 50; // Dense: 200 -300ms, 400 - 2s, 800 - 22s, 1600 - 2 min,
/// let strategy = "Damped".to_string();//
///
/// let strategy_params =
/// match strategy.as_str() {
/// "Naive" => None,
/// "Damped"=> Some(HashMap::from([("max_jac".to_string(),
/// None, ), ("maxDampIter".to_string(),
/// None, ), ("DampFacor".to_string(),
/// None, ) , ("adaptive".to_string(),
/// None, )
///
/// ])),
/// "Frozen" => Some(HashMap::from([("every_m".to_string(),
/// Some(Vec::from( [ 5 as f64] ))
/// )])),
/// &_=>panic!("Invalid strategy!")
///
///
/// };
/// let scheme = "forward".to_string();
/// let method = "Sparse".to_string();// or "Dense"
/// let linear_sys_method = None;
/// let ones = vec![0.0; values.len()*n_steps];
/// let initial_guess: DMatrix<f64> = DMatrix::from_column_slice(values.len(), n_steps, DVector::from_vec(ones).as_slice());
/// let mut BorderConditions = HashMap::new();
/// BorderConditions.insert("z".to_string(), vec![(0usize, 1.0f64)]);
/// BorderConditions.insert("y".to_string(), vec![(1usize, 1.0f64)]);
/// let Bounds = HashMap::from([ ("z".to_string(), (-10.0, 10.0), ), ("y".to_string(), (-7.0, 7.0), ) ]);
/// let rel_tolerance = HashMap::from([ ("z".to_string(), 1e-4 ), ("y".to_string(), 1e-4, ) ]);
/// assert_eq!(&eq_system.len(), &2);
/// let mut nr = BVP::new(eq_system,
/// initial_guess,
/// values,
/// arg,
/// BorderConditions, t0, t_end, n_steps, scheme, strategy, strategy_params, linear_sys_method, method, tolerance,
/// max_iterations, Some(rel_tolerance),Some(Bounds), None);
///
/// println!("solving system");
/// nr.solve();
/// nr.plot_result();
/// nr.save_to_file(None);
/// ```
//
/// BVP solver with collocation method
/// rewritten in Rust from Python code from SciPy
/// a collection of test examples of exect solutions of BVPs for testing purposes
/// RK45 and Dormand-Prince methods
/// solvers of nonlinear algebraic equations
/// general api for ODE solvers (BDF, RK4, etc.)
///
/// Example#1
/// ```
///use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use RustedSciThe::symbolic::symbolic_functions::Jacobian;
/// use RustedSciThe::numerical::ODE_api::ODEsolver;
///
/// //create instance of structure for symbolic equation system and Jacobian
/// let mut Jacobian_instance = Jacobian::new();
// define argument andunknown variables
/// let x = Expr::Var("x".to_string()); // argument
/// let y = Expr::Var("y".to_string());
/// let z:Expr = Expr::Var("z".to_string());
//define equation system
/// let eq1:Expr = Expr::Const(-1.0 as f64)*z.clone() - (Expr::Const(-1.0 as f64)*y.clone() ).exp();
/// let eq2:Expr = y;
/// let eq_system = vec![eq1, eq2];
// set unkown variables
/// let values = vec![ "z".to_string(), "y".to_string()];
// set argument
/// let arg = "x".to_string();
// set method
/// let method = "BDF".to_string();
// set initial conditions
/// let t0 = 0.0;
/// let y0 = vec![1.0, 1.0];
/// let t_bound = 1.0;
/// // set solver parameters (optional)
/// let first_step = None;
/// let atol = 1e-5;
/// let rtol = 1e-5;
/// let max_step = 1e-3;
/// let jac_sparsity = None;
/// let vectorized = false;
// create instance of ODE solver and solve the system
///let mut ODE_instance = ODEsolver::new_complex(
/// eq_system,
/// values,
/// arg,
/// method,
/// t0,
/// y0.into(),
/// t_bound,
/// max_step,
/// rtol,
/// atol,
/// jac_sparsity,
/// vectorized,
/// first_step);
/// ODE_instance.solve();
/// // plot the solution
/// ODE_instance.plot_result();
/// ODE_instance.save_result();
/// ```
/// Non-stiff equations: use ODE general api ODEsolver
/// RK45 and Dormand-Prince methods are available
/// Example#2
/// ```
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use RustedSciThe::numerical::ODE_api::ODEsolver;
/// //Example 2 the laziest way to solve ODE
/// // set RHS of system as vector of strings
/// let RHS = vec!["-z-exp(-y)", "y"];
/// // parse RHS as symbolic expressions
/// let Equations = Expr::parse_vector_expression(RHS.clone());
/// let values = vec![ "z".to_string(), "y".to_string()];
/// println!("Equations = {:?}", Equations);
/// // set argument
/// let arg = "x".to_string();
/// // set method
/// let method = "BDF".to_string();
/// // set initial conditions
/// let t0 = 0.0;
/// let y0 = vec![1.0, 1.0];
/// let t_bound = 1.0;
/// // set solver parameters (optional)
/// let first_step = None;
/// let atol = 1e-5;
/// let rtol = 1e-5;
/// let max_step = 1e-3;
/// let jac_sparsity = None;
/// let vectorized = false;
/// // create instance of ODE solver and solve the system
/// let mut ODE_instance = ODEsolver::new_complex(
/// Equations,
/// values,
/// arg,
/// method,
/// t0,
/// y0.into(),
/// t_bound,
/// max_step,
/// rtol,
/// atol,
/// jac_sparsity,
/// vectorized,
/// first_step
/// );
/// ODE_instance.solve();
/// ODE_instance.plot_result();
/// ODE_instance.save_result();
/// ```
/// Example#3
/// ```
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use RustedSciThe::numerical::ODE_api::ODEsolver;
/// let RHS = vec!["-z-y", "y"];
// parse RHS as symbolic expressions
/// let Equations = Expr::parse_vector_expression(RHS.clone());
/// let values = vec![ "z".to_string(), "y".to_string()];
/// println!("Equations = {:?}", Equations);
/// // set argument
/// let arg = "x".to_string();
/// // set method
/// let method = "DOPRI".to_string();
/// // set initial conditions
/// let t0 = 0.0;
/// let y0 = vec![1.0, 1.0];
/// let t_bound = 1.0;
/// // set solver parameters (optional)
///
/// let max_step = 1e-3;
///
/// // create instance of ODE solver and solve the system
/// let mut ODE_instance = ODEsolver::new_easy(
/// Equations,
/// values,
/// arg,
/// method,
/// t0,
/// y0.into(),
/// t_bound,
/// max_step,
/// );
/// ODE_instance.solve();
/// ODE_instance.plot_result();
/// ```
/// better universal api for all IVP solvers on board
/// use universal syntax with "new" function and choise of solvers with enum "SolverType"
/// ```
/// use RustedSciThe::numerical::ODE_api2::{UniversalODESolver, SolverType};
/// use RustedSciThe::numerical::Radau::Radau_main::RadauOrder;
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
///
/// use nalgebra::DVector;
/// let eq1 = Expr::parse_expression("-y");
/// let eq_system = vec![eq1];
/// let values = vec!["y".to_string()];
/// let arg = "t".to_string();
/// let t0 = 0.0;
/// let y0 = DVector::from_vec(vec![1.0]);
/// let t_bound = 0.5;
///
/// let mut solver = UniversalODESolver::new(
/// eq_system,
/// values,
/// arg,
/// SolverType::Radau(RadauOrder::Order3),
/// t0,
/// y0,
/// t_bound,
/// );
/// solver.set_max_iterations(100);
/// solver.set_tolerance(1e-6);
/// solver.set_step_size(1e-3);
/// solver.initialize();
/// solver.solve();
/// let (t_result, y_result) = solver.get_result();
/// ```
/// or use shortcuts for every solver
/// ```
/// use RustedSciThe::numerical::ODE_api2::UniversalODESolver;
/// use RustedSciThe::numerical::Radau::Radau_main::RadauOrder;
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
/// use nalgebra::DVector;
/// let eq1 = Expr::parse_expression("-y");
/// let eq_system = vec![eq1];
/// let values = vec!["y".to_string()];
/// let arg = "t".to_string();
/// let t0 = 0.0;
/// let y0 = DVector::from_vec(vec![1.0]);
/// let t_bound = 0.5;
///
/// let mut solver = UniversalODESolver::radau(
/// eq_system,
/// values,
/// arg,
/// RadauOrder::Order3,
/// t0,
/// y0,
/// t_bound,
/// 1e-6,
/// 50,
/// Some(1e-3),
/// );
///
/// solver.solve();
/// let (t_result, y_result) = solver.get_result();
/// ```
/// Radau solver (good for nonlinear ODEs)
/// #############################END OF ODEs SECTIONS#####
///
/// Example#1
/// ```
/// use RustedSciThe::symbolic::symbolic_engine::Expr;
///
/// use RustedSciThe::numerical::Radau::Radau_main::{Radau, RadauOrder};
/// use approx::assert_relative_eq;
/// use nalgebra::DMatrix;
/// use nalgebra::DVector;
/// use simplelog::*;
/// // Test system: y1' = -2*y1 + y2, y2' = y1 - 2*y2
/// // Initial conditions: y1(0) = 1, y2(0) = 0
/// // solution: y1(t) = 1/2 e^(-3 x) (e^(2 x) + 1)
/// // y2(t) = 1/2 e^(-3 x) (-1 + e^(2 x))
/// let eq1 = Expr::parse_expression("-2*y1+y2");
/// let eq2 = Expr::parse_expression("y1-2*y2");
/// let eq_system = vec![eq1, eq2];
///
/// let values = vec!["y1".to_string(), "y2".to_string()];
/// let arg = "t".to_string();
/// let tolerance = 1e-6;
/// let max_iterations = 50;
/// let h = Some(1e-3);
/// let t0 = 0.0;
/// let t_bound = 1.0;
/// let y0 = DVector::from_vec(vec![1.0, 0.0]);
///
/// let mut radau = Radau::new(RadauOrder::Order3);
/// radau.set_initial(
/// eq_system,
/// values,
/// arg,
/// tolerance,
/// max_iterations,
/// h,
/// t0,
/// t_bound,
/// y0,
/// );
///
/// radau.solve();
///
/// assert_eq!(radau.status, "finished");
/// let (_, y_result) = radau.get_result();
/// let y_res = y_result.unwrap();
///
/// ```
/// shooting method for solving BVP
/// collection of optimization algorithms