Curvature Matrices (optional material!)
		• Each element in the curvature matrix specifies how the gradient in one direction changes as we move in some other direction. • For a linear network with a squared error, the curvature matrix of the error, E, is the covariance matrix of the inputs. • The reason steepest descent goes wrong is that the ratio of the magnitudes of the gradients for different weights changes as we move down the gradient.
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