Worked-Out Example - 10.1.6 | 10. Modified Euler’s Method | Mathematics - iii (Differential Calculus) - Vol 4
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Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Introduction to Modified Euler's Method

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0:00
Teacher
Teacher

Today, we're exploring the Modified Euler’s Method, which helps us find numerical solutions to differential equations more accurately. Can anyone tell me why we can't always use exact analytical solutions?

Student 1
Student 1

Sometimes the differential equations are too complex to solve analytically!

Teacher
Teacher

Exactly! That's why we have numerical methods. The Modified Euler's Method improves the accuracy of the basic Euler's method by averaging slopes. Does anyone remember how the basic Euler's method works?

Student 2
Student 2

It's about using the slope at the start of the interval to predict the next point.

Teacher
Teacher

That's right! Now, Modified Euler's adjusts this prediction by considering the slope at both the beginning and the end. Think of it as checking where you're going halfway through the journey. Ready to dive into an example?

Worked-Out Example Setup

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0:00
Teacher
Teacher

Let's set up our first example. We have the equation \( \frac{dy}{dx} = x + y \) with initial condition \( y(0) = 1 \). What step size do we have?

Student 3
Student 3

We have a step size of 0.1!

Teacher
Teacher

Correct! Now, can anyone tell me the initial values we will be using?

Student 4
Student 4

So, \( x_0 = 0 \) and \( y_0 = 1 \)?

Teacher
Teacher

Yes! Now we are ready to take our first step using the Modified Euler's Method!

First Iteration Breakdown

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0:00
Teacher
Teacher

Let's begin our first iteration. We first need to calculate \( k_1 \). Who can tell me what \( k_1 \) is?

Student 1
Student 1

It's \( f(x_0, y_0) \), which is \( 0 + 1 = 1 \)!

Teacher
Teacher

Great! So, what’s our predicted \( y^* \)?

Student 2
Student 2

\( y^* = 1 + 0.1 \cdot 1 = 1.1 \)!

Teacher
Teacher

Perfect! Now how do we calculate \( k_2 \)?

Student 3
Student 3

It's \( f(0.1, 1.1) \), which gives us \( 0.1 + 1.1 = 1.2 \)!

Teacher
Teacher

Well done! Finally, how do we get the corrected value \( y_1 \)?

Student 4
Student 4

\( y_1 = 1 + \frac{0.1}{2} (1 + 1.2) = 1.11! \)

Second Iteration Analysis

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0:00
Teacher
Teacher

Moving on to the second iteration! What are our new values for \( x \) and \( y \)?

Student 1
Student 1

\( x_1 = 0.1 \) and \( y_1 = 1.11 \).

Teacher
Teacher

Yes! Now, what is \( k_1 \) for this step?

Student 2
Student 2

It will be \( f(0.1, 1.11) = 0.1 + 1.11 = 1.21 \)!

Teacher
Teacher

Wonderful! Now let's predict \( y^* \). What do we have?

Student 3
Student 3

\( y^* = 1.11 + 0.1 \cdot 1.21 = 1.231 \)!

Teacher
Teacher

Great job! Finally, let’s compute \( k_2 \) and our corrected value!

Student 4
Student 4

For \( k_2 \), we find \( f(0.2, 1.231) = 1.431 \), and the corrected \( y_2 \) is about \( 1.24205 \)!

Conclusion and Summary

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0:00
Teacher
Teacher

To summarize, how did we find our final value using the Modified Euler’s Method?

Student 1
Student 1

We iterated twice, using the slopes to predict and then correct our values.

Student 2
Student 2

We ended with \( y(0.2) \approx 1.24205 \)!

Teacher
Teacher

Exactly! The Modified Euler's method provides a much better approximation than standard Euler’s method by taking the average of slopes. Any final questions?

Student 3
Student 3

How does this compare to higher order methods like Runge-Kutta?

Teacher
Teacher

Great question! While Modified Euler's is simple and quite effective, methods like Runge-Kutta offer even greater accuracy, though at the cost of more function evaluations.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section provides a detailed worked-out example of using the Modified Euler’s Method to approximate the solution of a first-order ordinary differential equation.

Standard

In this section, the application of the Modified Euler’s Method is demonstrated through a step-by-step worked-out example. The example illustrates how to predict and correct the value of a differential equation at a specific point, emphasizing the method's improved accuracy over standard Euler's method.

Detailed

Worked-Out Example

Introduction

This section presents a detailed example of using the Modified Euler's Method (also known as Heun's Method or the Improved Euler Method) to find an approximate solution of the initial value problem (IVP) defined by the differential equation
$$ \frac{dy}{dx} = x + y, \quad y(0) = 1, \quad h = 0.1. $$

Step-by-Step Solution

  1. Initial Values: The initial values are set as follows:
  2. $$x_0 = 0$$
  3. $$y_0 = 1$$
  4. $$h = 0.1$$
  5. First Iteration:
  6. Compute the initial slope:
    $$k_1 = f(x_0, y_0) = 0 + 1 = 1$$
  7. Predict the next value:
    $$y^* = y_0 + h \cdot k_1 = 1 + 0.1 \cdot 1 = 1.1$$
  8. Compute the corrected slope:
    $$k_2 = f(0.1, 1.1) = 0.1 + 1.1 = 1.2$$
  9. Calculate the corrected value:
    $$y_1 = y_0 + \frac{h}{2} (k_1 + k_2) = 1 + 0.05(1 + 1.2) = 1.11$$
  10. Second Iteration:
  11. Update the values:
    • $$x_1 = 0.1, y_1 = 1.11$$
  12. Compute the new slope:
    $$k_1 = f(0.1, 1.11) = 0.1 + 1.11 = 1.21$$
  13. Predict the next value:
    $$y^* = 1.11 + 0.1 \cdot 1.21 = 1.231$$
  14. Correct the slope:
    $$k_2 = f(0.2, 1.231) = 0.2 + 1.231 = 1.431$$
  15. Calculate the corrected value:
    $$y_2 = 1.11 + \frac{h}{2} (k_1 + k_2) = 1.11 + 0.05(1.21 + 1.431) = 1.24205$$

Conclusion

The final approximation is
$$ y(0.2) \approx 1.24205 $$, illustrating the Modified Euler's Method as a more accurate alternative to the basic Euler Method.

Youtube Videos

interpolation problem 1|| Newton's forward interpolation formula|| numerical methods
interpolation problem 1|| Newton's forward interpolation formula|| numerical methods

Audio Book

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Initial Values Setup

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  • Step 1: Initial values
  • 𝑥 = 0, 𝑦 = 1, ℎ = 0.1

Detailed Explanation

In this step, we establish the initial values needed for the Modified Euler's Method. Here, we set the initial value of 𝑥 to 0 and the initial value of 𝑦 to 1. The step size ℎ is set to 0.1, indicating that we will compute the function's value in increments of 0.1 from the starting point.

Examples & Analogies

Imagine you're planning a short road trip. You start your journey at mile marker 0 (your starting point), and you know you'll be traveling 0.1 miles at a time. The initial mile marker (𝑥) is 0, and your car’s initial mileage (𝑦) is 1 mile. You are ready to start this trip.

First Iteration Calculation

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  • Step 2: First Iteration
  • 𝑘 = 𝑓(𝑥 ,𝑦 ) = 0 +1 = 1
  • Predictor:
    𝑦∗ = 𝑦 +ℎ ⋅𝑘 = 1+ 0.1⋅1 = 1.1
  • 𝑘 = 𝑓(𝑥 ,𝑦∗) = 𝑓(0.1,1.1) = 0.1 +1.1 = 1.2
  • Corrected value:
    ℎ𝑦 = 𝑦 + (𝑘 + 𝑘 ) = 1 + (1+ 1.2) = 1+ 0.1⋅1.1 = 1.11

Detailed Explanation

In the first iteration, we calculate the value of 𝑘 by substituting the initial values into the function 𝑓. Here, 𝑖𝑓(𝑥 ,𝑦 ) gives us 1. Next, we predict the next value 𝑦∗ using the formula provided, resulting in 1.1. We then compute another 𝑘 using the predicted value 𝑦∗ before determining the corrected value of 𝑦, which gives us approximately 1.11 at the end of the first step.

Examples & Analogies

Continuing with our road trip, after traveling from the starting point, you assess how far you've come based on the current mileage and then predict how far you will be after the next increment. You also refine your estimate by recalculating based on your new position along the route, arriving at a slightly adjusted distance from the start.

Second Iteration Calculation

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  • Step 3: Second Iteration
  • 𝑥 = 0.1, 𝑦 = 1.11
  • 𝑘 = 𝑓(0.1,1.11) = 0.1 +1.11 = 1.21
  • Predictor:
    𝑦∗ = 1.11+ 0.1⋅1.21 = 1.231
  • 𝑘 = 𝑓(0.2,1.231) = 0.2 +1.231 = 1.431
  • Corrected value:
    𝑦 = 1.11+ (1.21 +1.431) = 1.11 +0.1 ⋅1.3205 = 1.24205

Detailed Explanation

In the second iteration, we use the updated values of 𝑥 and 𝑦 from the first iteration. We calculate 𝑘 again, yielding a value of 1.21. Using this, we predict 𝑦∗ to be 1.231. After computing a new 𝑘 for 𝑦∗, we find the corrected value of 𝑦 to be approximately 1.24205, after averaging the slopes and adjusting our original estimate.

Examples & Analogies

On your road trip, after traveling a short distance, you double-check your route to see if you're on track. You re-evaluate your speed for the next leg of your journey and adjust your expected arrival marker based on this newly acquired info, resulting in a slightly adjusted mileage that reflects your real-time position.

Final Result

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  • Final Answer:
  • 𝑦(0.2) ≈ 1.24205

Detailed Explanation

At this point, we have completed the calculations required by the Modified Euler's Method. The approximated value of 𝑦 at 𝑥 = 0.2 is around 1.24205. This gives us a better understanding of how the solution behaves after applying the numerical method over the specified interval.

Examples & Analogies

After your road trip, you take a moment to reflect on the journey. You've successfully navigated to your destination, realizing how much more accurate your estimates were thanks to your careful recalculations along the way. Just like how you reach an accurate mark on your journey, we arrive at a close approximation of y using the Modified Euler's Method.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Modified Euler’s Method: A second-order numerical technique that improves the accuracy of Euler's method by averaging slopes.

  • Initial Value Problem: A problem where the initial condition of a function is known, and the goal is to find its values at subsequent points.

  • Slope Calculation: Key in both the prediction and correction steps of the Modified Euler’s Method.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • Using Modified Euler's Method on the equation \( \frac{dy}{dx} = x + y \) with \( y(0) = 1 \) gives a sequence of approximations leading to \( y(0.2) \approx 1.24205 \).

  • An initial value problem for a first-order ODE for a different equation can also be approached similarly using the same method.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • To find that y, don't just guess, use k's and h, it's for the best!

📖 Fascinating Stories

  • Once upon a time, two slopes met on a hill, one said follow me, the other to stand still. Together they took a step down, and found a better point around.

🧠 Other Memory Gems

  • Use Kappa to Stay True with Modified Euler: K1, predict, K2, average!

🎯 Super Acronyms

M.E.M. - Modified Euler's Method means More Effective Model!

Flash Cards

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Glossary of Terms

Review the Definitions for terms.

  • Term: Modified Euler’s Method

    Definition:

    A numerical method to solve initial value problems more accurately than the standard Euler's method by using the average of the slopes at the start and end of the interval.

  • Term: Firstorder ODE

    Definition:

    An ordinary differential equation involving the first derivative of a function.

  • Term: Initial Value Problem (IVP)

    Definition:

    A type of problem where the solution of the differential equation is determined by the value of the function at a specific point.

  • Term: Slope

    Definition:

    The rate of change of a function, often represented as the derivative.