Chapter 21: Problem 6
(Loeistic population) \(y^{\prime}=y-y^{2}, y(0)=0.2, h=0.1\)
Short Answer
Expert verified
The next steps are approximately: \( y_1 = 0.216 \), \( y_2 = 0.2329344 \), \( y_3 = 0.25080108287 \).
Step by step solution
01
Understand the Initial Condition and Equation
We are given a differential equation \( y' = y - y^2 \) with an initial condition \( y(0) = 0.2 \). The task is to find the approximate solution using an initial value method with a step size \( h = 0.1 \). This problem suggests using Euler's method, a numerical technique to solve differential equations.
02
Set Up Euler’s Method Formula
Euler's method approximates the solution of a differential equation by taking small steps of size \( h \). The formula for updating the solution is given by: \[ y_{n+1} = y_n + h imes f(t_n, y_n) \]where \( f(t, y) = y - y^2 \) in this case, and \( t_n = nh \).
03
Initialize Variables
Start the method with the initial condition \( t_0 = 0 \) and \( y_0 = 0.2 \). We will compute the next few iterations manually for clarity.
04
First Iteration
Compute \( y_1 \) using Euler's formula:1. Compute \( f(t_0, y_0) = y_0 - y_0^2 = 0.2 - 0.2^2 = 0.2 - 0.04 = 0.16 \).2. Update \( y_1 = y_0 + h imes f(t_0, y_0) = 0.2 + 0.1 imes 0.16 = 0.2 + 0.016 = 0.216 \).
05
Second Iteration
Repeat the process to find \( y_2 \):1. Compute \( f(t_1, y_1) = y_1 - y_1^2 = 0.216 - 0.216^2 = 0.216 - 0.046656 = 0.169344 \).2. Update \( y_2 = y_1 + h imes f(t_1, y_1) = 0.216 + 0.1 imes 0.169344 = 0.216 + 0.0169344 = 0.2329344 \).
06
Third Iteration
Now compute \( y_3 \) using previously obtained \( y_2 \):1. Compute \( f(t_2, y_2) = y_2 - y_2^2 = 0.2329344 - 0.2329344^2 = 0.2329344 - 0.0542675713 = 0.1786668287 \).2. Update \( y_3 = y_2 + h imes f(t_2, y_2) = 0.2329344 + 0.1 imes 0.1786668287 = 0.2329344 + 0.01786668287 = 0.25080108287 \).
07
Summary of Values
So far, we have computed several approximations:- \( y_0 = 0.2 \)- \( y_1 = 0.216 \)- \( y_2 = 0.2329344 \)- \( y_3 = 0.25080108287 \)These values represent the approximate solution at each step using Euler's method.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Numerical Methods
Numerical methods play a critical role in finding approximate solutions to complex mathematical problems. In particular, they are extremely useful when dealing with differential equations that do not have straightforward analytical solutions. Euler's Method, a fundamental numerical approach, is designed to find an approximate solution by following the curve of the function step by step.
In the context of our exercise, Euler's Method provides a practical manner of estimating solutions by moving through small increments, or 'steps', denoted as \( h \). This approach breaks down the process into manageable computations, using known initial values to predict future states through iterative calculations.
In the context of our exercise, Euler's Method provides a practical manner of estimating solutions by moving through small increments, or 'steps', denoted as \( h \). This approach breaks down the process into manageable computations, using known initial values to predict future states through iterative calculations.
- Step size \( h \) determines the precision of results - smaller steps lead to more accurate approximations.
- The method updates the variable of interest using a formula: \( y_{n+1} = y_n + h \times f(t_n, y_n) \).
- It is especially useful for initial value problems, where solutions evolve over a defined starting condition.
Differential Equations
Differential equations are mathematical expressions that describe the relationship between a function and its derivatives. These equations are essential in modeling real-world phenomena where change is continuous, such as population growth, chemical reactions, or motion dynamics.
In our example, the given differential equation \( y' = y - y^2 \) illustrates an aspect of population dynamics resembling a logistic growth model. Here, \( y' \) represents the rate of change in population, and the equation outlines how this rate depends on the current population \( y \). In many scenarios like this, it can be difficult or even impossible to find exact solutions through algebraic means.
In our example, the given differential equation \( y' = y - y^2 \) illustrates an aspect of population dynamics resembling a logistic growth model. Here, \( y' \) represents the rate of change in population, and the equation outlines how this rate depends on the current population \( y \). In many scenarios like this, it can be difficult or even impossible to find exact solutions through algebraic means.
- Understanding the behavior of solutions involves identifying variables and how they influence change over time.
- Solutions to differential equations can often predict future trends and states of a process, provided initial conditions.
- Euler's Method helps approximate these solutions when an explicit solution isn't easily obtainable analytically.
Initial Value Problems
Initial value problems (IVPs) in mathematics are a type of differential equation that comes with a specified initial condition. This initial condition states the value of the function at the start of the observation period. It is crucial because it starts the process of finding a solution that evolves over time.
In the exercise example, the initial value problem begins with the condition \( y(0) = 0.2 \). This tells us the starting point for our solution, allowing us to 'anchor' our predictions based on this known state. Using such a starting point:
In the exercise example, the initial value problem begins with the condition \( y(0) = 0.2 \). This tells us the starting point for our solution, allowing us to 'anchor' our predictions based on this known state. Using such a starting point:
- The solution trajectory is determined uniquely, governing how the function behaves as \( t \) progresses.
- The numerical tools like Euler's Method leverage these conditions to simulate responses accurately over a number of discrete steps.
- Initial conditions significantly influence the outcomes of the solutions, highlighting their importance in calculations.