Gradient Descent and Cauchy Method in Differential Equations

In summary, the Cauchy method is an optimization algorithm that finds the minimum value of a function by iteratively moving in the direction of steepest descent. It is a specific type of gradient method and is often used in machine learning and optimization problems. The gradient method works by updating the current point based on the direction of steepest descent until a stopping criterion is met. However, both methods can be slow to converge, may get stuck in local minima, and require the function to be differentiable. In high dimensional problems, they may also suffer from the "curse of dimensionality."
  • #1
kidsasd987
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http://www.math.uiuc.edu/documenta/vol-ismp/40_lemarechal-claude.pdf



I don't understand why we use theta for equation (1)

Θ>0

but why α=-θX?



Thanks.
 
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  • #2
It was already given that X is the derivative with respect to x and so [itex]\theta X[/itex] is gives a slight change along the tangent plane in the x direction. I presume it is negative because they want to think of [itex]\theta[/itex] going to 0 as the point, [itex](x_0- \theta X, y_0- \theta Y, z_0-\theta Z)[/itex], moving toward [itex](x_0, y_0, z_0)[/itex] along the path defined by the differential equation.
 
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Related to Gradient Descent and Cauchy Method in Differential Equations

1. What is the Cauchy method?

The Cauchy method, also known as the steepest descent method, is an optimization algorithm used to find the minimum value of a function. It iteratively moves in the direction of steepest descent, calculated using the gradient of the function at the current point, in order to reach the minimum.

2. How is the Cauchy method different from the gradient method?

The Cauchy method is a specific type of gradient method that uses the steepest descent direction at each iteration. Other gradient methods may use different descent directions, such as the conjugate gradient method which takes into account previous iterations.

3. What is the gradient method used for?

The gradient method is used to find the minimum value of a function. It is often used in machine learning and optimization problems where the goal is to minimize a cost or error function.

4. How does the gradient method work?

The gradient method works by iteratively updating the current point based on the direction of steepest descent, calculated using the gradient of the function at that point. This process continues until a stopping criterion is met, such as reaching a certain number of iterations or a small enough change in the function value.

5. What are the limitations of the Cauchy and gradient methods?

The Cauchy and gradient methods can be slow to converge and may get stuck in local minima. They also require the function to be differentiable. In high dimensional problems, they may also suffer from the "curse of dimensionality" where the number of iterations needed to converge increases exponentially with the number of variables.

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