# getState-method: getState In f0nzie/rODE: Ordinary Differential Equation (ODE) Solvers Written in R Using S4 Classes

## Description

Get current state of the system

## Usage

 `1` ```getState(object, ...) ```

## Arguments

 `object` a class object `...` additional parameters

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61``` ```# ++++++++++++++++++++++++++++++++++++++++++++++++ application: VanderPolApp.R # Solution of the Van der Pol equation # importFromExamples("VanderPol.R") # run the application VanderpolApp <- function(verbose = FALSE) { # set the orbit into a predefined state. y1 <- 2; y2 <- 0; dt <- 0.1; rigid_body <- VanderPol(y1, y2) solver <- RK45(rigid_body) rowVector <- vector("list") i <- 1 while (getState(rigid_body)[3] <= 20) { rowVector[[i]] <- list(t = getState(rigid_body)[3], y1 = getState(rigid_body)[1], y2 = getState(rigid_body)[2]) solver <- step(solver) rigid_body <- getODE(solver) i <- i + 1 } DT <- data.table::rbindlist(rowVector) return(DT) } # show solution solution <- VanderpolApp() plot(solution) # ++++++++++++++++++++++++++++++++++++++++++++++++++application: SpringRK4App.R # Simulation of a spring considering no friction importFromExamples("SpringRK4.R") # run application SpringRK4App <- function(verbose = FALSE) { theta <- 0 thetaDot <- -0.2 tmax <- 22; dt <- 0.1 spring <- SpringRK4() spring@state[3] <- 0 # set time to zero, t = 0 spring <- setState(spring, theta, thetaDot) # spring <- setStepSize(spring, dt = dt) # using stepSize in RK4 spring@odeSolver <- setStepSize(spring@odeSolver, dt) # set new step size rowvec <- vector("list") i <- 1 while (getState(spring)[3] <= tmax) { rowvec[[i]] <- list(t = getState(spring)[3], # angle y1 = getState(spring)[1], # derivative of the angle y2 = getState(spring)[2]) # time i <- i + 1 spring <- step(spring) } DT <- data.table::rbindlist(rowvec) return(DT) } # show solution solution <- SpringRK4App() plot(solution) ```

f0nzie/rODE documentation built on May 14, 2019, 10:34 a.m.