نتایج جستجو برای: hessian matrix
تعداد نتایج: 366902 فیلتر نتایج به سال:
Active-set quadratic programming (QP) methods use a working set to define the search direction and multiplier estimates. In the method proposed by Fletcher in 1971, and in several subsequent mathematically equivalent methods, the working set is chosen to control the inertia of the reduced Hessian, which is never permitted to have more than one nonpositive eigenvalue. (We call such methods inert...
We present a regularized Gauss-Newton method for solving the inverse problem of parameter reconstruction from boundary data in frequency-domain diffuse optical tomography. To avoid the explicit formation and inversion of the Hessian which is often prohibitively expensive in terms of memory resources and runtime for large-scale problems, we propose to solve the normal equation at each Newton ste...
We investigate the universal property of curvatures in surface models that display a flat phase and a rough phase whose criticality is described by the Gaussian model. Earlier we derived a relation between the Hessian of the free energy and the Gaussian coupling constant in the six-vertex model. Here we show its validity in a general setting using renormalization group arguments. The general va...
In this paper, we consider smooth convex approximations to the maximum eigenvalue function. To make it applicable to a wide class of applications, the study is conducted on the composite function of the maximum eigenvalue function and a linear operator mapping m to n, the space of n-by-n symmetric matrices. The composite function in turn is the natural objective function of minimizing the maxim...
Many problems of theoretical and practical interest involve finding a convex or concave function. For instance, optimization problems such as finding the projection on the convex functions in Hk(Ω), or some problems in economics. In the continuous setting and assuming smoothness, the convexity constraints may be given locally by asking the Hessian matrix to be positive semidefinite, but in maki...
This work considers the effectiveness of using anisotropic coordinate transformation in adaptive mesh generation. The anisotropic coordinate transformation is derived by interpreting the Hessian matrix of the data function as a metric tensor that measures the local approximation error. The Hessian matrix contains information about the local curvature of the surface and gives guidance in the asp...
Newton-type methods and quasi-Newton methods have proven to be very successful in solving dense unconstrained optimization problems. Recently there has been considerable interest in extending these methods to solving large problems when the Hessian matrix has a known a priori sparsity pattern, This paper treats sparse quasi-Newton methods in a uniform fashion and shows the effect of loss of pos...
Second-order methods for neural network optimization have several advantages over methods based on first-order gradient descent, including better scaling to large mini-batch sizes and fewer updates needed for convergence. But they are rarely applied to deep learning in practice because of high computational cost and the need for model-dependent algorithmic variations. We introduce a variant of ...
The traditional quasi-Newton method for updating the approximate Hessian is based on the change in the gradient of the objective function. This paper describes a new update method that incorporates also the change in the value of the function. The method effectively uses a cubic approximation of the objective function to better approximate its directional second derivative. The cubic approximat...
A batch training algorithm for feed-forward networks is proposed which uses Newton’s method to estimate a vector of optimal learning factors, one for each hidden unit. Backpropagation, using this learning factor vector, is used to modify the hidden unit’s input weights. Linear equations are then solved for the network’s output weights. Elements of the new method’s Gauss-Newton Hessian matrix ar...
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