[Insight-users] Gradient descent and local minima?

[Kevin H. Hobbs]

On 02/01/2010 07:53 AM, motes motes wrote:
> I am currently using the gradient descent optimizer and the
> MeanSquaresImageToImageMetric in an image registration apllication
> used for CD scans of lungs.
> 
> But how do I know that the minima reached is not just a local minima
> instead of the global minima?

The short answer is that one can never know if a multi-dimensional
optimization has reached the global minimum.

The best you can do is show that repeated optimizations with different
initial conditions reach the "same" final point, and that that point is
no worse than any other point found.

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