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I came across the following:

"Let f be continuously differentiable with Lipschitz gradient, i.e.,

$ ||\nabla f(\mathbf{x}) - \nabla f(\mathbf{y})|| \leq L||(\mathbf{x} - \mathbf{y})|| $

where L is the modulus of the Hessian (if exists)."

What is the modulus of a matrix? Is it the same thing as the determinant?

Thanks!

2 Answers 2