---
title: "BCR 06 Sept"
author: "Jonathan Herrewijnen"
date: "September 6, 2018"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```

## R Markdown

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When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document. You can embed an R code chunk like this:

```{r cars}
summary(cars)
```

## Including Plots

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```{r pressure, echo=FALSE}
plot(pressure)
```

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//CBR Two dimensional phase portraits, equilibria and stability

```{r}
#install.packages("phaseR")
library("phaseR")

# define 2D ODE model
model = function(timepoint, state, parameters) {
with(as.list(c(state, parameters)), {
dx = -2 * x - 3 * y
dy = -x - 2 * y
list(c(dx, dy))
})
}
# for setting the axis limits
xlim = c(-10, 10)
ylim = c(-10, 10)
# no parameters in the ODE, so we set pars as an empty vector
pars = vector()

# draw vector field
model.flowField = flowField(xlab = "x", ylab = "y", model, xlim = xlim, ylim = ylim,
parameters = pars, points = 19, add = FALSE, state.names = c("x", "y"))

# draw nullclines
model.nullclines = nullclines(model, xlim = xlim, ylim = ylim, parameters = pars,
points = 500, state.names = c("x", "y"))

# draw trajectory
model.trajectory = trajectory(model, y0 = c(-5, -5), tlim = c(0, 10), parameters = pars,
state.names = c("x", "y"))

```

//Numerical Solution

```{r}
# perform numerical simulation and plot end result
model.numericalSolution = numericalSolution(model, y0 = c(-5, -5), tlim = c(0,
20), type = "one", parameters = pars, col = c("green", "orange"), ylim = ylim,
add.legend = F)

# make legend for plot
legend("topright", col = c("green", "orange"), legend = c("x", "y"), lty = 1)

# after the next command, click mouse to find values of a point within the
# phase portrait (e.g., to approximate the value of an equilibrium)

eq = locator(n = 1)
eq
```

//QUESTION 1

The 0, 0 location was determined from the first phase portrait!
Not from the second click portrait!

```{r}
#?stability

stability(model, ystar = c(0, 0))
#stability(deriv, ystar = NULL, parameters = NULL, system = "two.dim", h = 1e-07, summary = TRUE, state.names = c("x", "y"))


```

//Question 2
Meaning of T and Delta.

T=(I THINK!) the value of the equilibrium at dx/dt=0 -> So for the equilibrium, in our case the equilibrium is stable.
Delta="In the two dimensional system case, value of the Jacobians determinant at y.star. ->So the Jacobian matrix

//Question 3: PhasePlaneAnalysis

```{r}
# perform phase plane analysis
phasePlaneAnalysis(model, xlim = xlim, ylim = ylim, parameters = pars)
```

//QUESTION 4-8
```{r}
library("phaseR")
# define 2D ODE model
model = function(timepoint, state, parameters) {
with(as.list(c(state, parameters)), {
  
#Question 4
dx = -x + (2 * y)
dy = (-5 * x) - y
  
#Question 5
#dx = -3*x -2*y
#dy = -2*x -y

list(c(dx, dy))
})
}

# for setting the axis limits
xlim = c(-10, 10)
ylim = c(-10, 10)

# no parameters in the ODE, so we set pars as an empty vector
pars = vector()

#Determine Stability
stability(model, ystar = c(0, 0))

# perform phase plane analysis
phasePlaneAnalysis(model, xlim = xlim, ylim = ylim, parameters = pars)
```