Monte Carlo-Based Covariance Matrix of Residuals and Critical Values in Minimum L1-Norm

Vector-based spatial-temporal minimum L1-norm solution for MEG.

Minimum L1-norm solutions have been used by many investigators to analyze MEG responses because they provide high spatial resolution images. However, conventional minimum L1-norm approaches suffer from instability in spatial construction, and poor smoothness of the reconstructed source time-courses. Activity commonly "jumps" from one grid point to (usually) the neighboring grid points. Equivale...

On Monte Carlo and Quasi-Monte Carlo for Matrix Computations

Transition Matrix Monte Carlo

Although histogram methods have been extremely effective for analyzing data from Monte Carlo simulations, they do have certain limitations, including the range over which they are valid and the difficulties of combining data from independent simulations. In this paper, we describe an complementary approach to extracting information from Monte Carlo simulations that uses the matrix of transition...

Minimax Estimation of Large Covariance Matrices under l1-Norm

Driven by a wide range of applications in high-dimensional data analysis, there has been significant recent interest in the estimation of large covariance matrices. In this paper, we consider optimal estimation of a covariance matrix as well as its inverse over several commonly used parameter spaces under the matrix l1 norm. Both minimax lower and upper bounds are derived. The lower bounds are ...

ec adoption and critical success factors of ec in smes in iran

تجارت الکترونیکی شیوه اجرای مسئولیتها، تقابل با مشتریان و امور معمول عملیاتی در شرکتها را تغییر داده است. تجارت الکترونیکی در عمل تنها خرید و فروش کالاها را از طریق ابزار الکترونیک نمی باشد، بلکه تمام فعالیتهای لازم جهت انجام فرایند فروش را نیز در بر میگیرد. در اواخر دهه 1990 بسیاری از شرکتها فعالیتهای خود را به منظور دستیابی به مشتریان جدید و یا ارائه فرصتهای جدید به مشتریان موجود گسترش دادند...