共查询到20条相似文献,搜索用时 140 毫秒
1.
针对恒模算法(CMA)收敛速度较慢、收敛后均方误差较大的缺点,提出一种新的双模式盲均衡算法.在算法初期,利用能快速收敛的归一化恒模算法(NCMA)进行冷启动,在算法收敛后切换到判决引导(DD-LMS)算法,减少误码率.计算机仿真表明,提出的新算法有较快的收敛速度和较低的误码率. 相似文献
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We describe a fraction free version of the Matrix Berlekamp/Massey algorithm. The algorithm computes a minimal matrix generator of linearly generated square matrix sequences in an integral domain. The algorithm performs all operations in the integral domain, so all divisions performed are exact. For scalar sequences, the matrix algorithm specializes to a different algorithm than the algorithm currently in the literature. This new scalar algorithm has smaller intermediate values than the known fraction free Berlekamp/Massey algorithm. 相似文献
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Yaguang Yang 《Numerical Algorithms》2017,74(4):967-996
Mehrotra’s algorithm has been the most successful infeasible interior-point algorithm for linear programming since 1990. Most popular interior-point software packages for linear programming are based on Mehrotra’s algorithm. This paper describes a proposal and implementation of an alternative algorithm, an arc-search infeasible interior-point algorithm. We will demonstrate, by testing Netlib problems and comparing the test results obtained by the arc-search infeasible interior-point algorithm and Mehrotra’s algorithm, that the proposed arc-search infeasible interior-point algorithm is a more reliable and efficient algorithm than Mehrotra’s algorithm. 相似文献
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针对模糊C均值算法用于图像分割时对初始值敏感、容易陷入局部极值的问题,提出基于混合单纯形算法的模糊均值图像分割算法.算法利用Nelder-Mead单纯形算法计算量小、搜索速度快和粒子群算法自适应能力强、具有较好的全局搜索能力的特点,将混合单纯形算法的结果作为模糊C均值算法的输入,并将其用于图像分割.实验结果表明:基于混合单纯形算法的模糊均值图像分割算法在改善图像分割质量的同时,提高了算法的运行速度. 相似文献
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提出了一种凸组合共轭梯度算法,并将其算法应用到ARIMA模型参数估计中.新算法由改进的谱共轭梯度算法与共轭梯度算法作凸组合构造而成,具有下述特性:1)具备共轭性条件;2)自动满足充分下降性.证明了在标准Wolfe线搜索下新算法具备完全收敛性,最后数值实验表明通过调节凸组合参数,新算法更加快速有效,通过具体实例证实了模型... 相似文献
7.
A descent algorithm for nonsmooth convex optimization 总被引:1,自引:0,他引:1
Masao Fukushima 《Mathematical Programming》1984,30(2):163-175
This paper presents a new descent algorithm for minimizing a convex function which is not necessarily differentiable. The
algorithm can be implemented and may be considered a modification of the ε-subgradient algorithm and Lemarechal's descent
algorithm. Also our algorithm is seen to be closely related to the proximal point algorithm applied to convex minimization
problems. A convergence theorem for the algorithm is established under the assumption that the objective function is bounded
from below. Limited computational experience with the algorithm is also reported. 相似文献
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This paper presents a new composite sub-steps algorithm for solving reliable numerical responses in structural dynamics. The newly developed algorithm is a two sub-steps, second-order accurate and unconditionally stable implicit algorithm with the same numerical properties as the Bathe algorithm. The detailed analysis of the stability and numerical accuracy is presented for the new algorithm, which shows that its numerical characteristics are identical to those of the Bathe algorithm. Hence, the new sub-steps scheme could be considered as an alternative to the Bathe algorithm. Meanwhile, the new algorithm possesses the following properties: (a) it produces the same accurate solutions as the Bathe algorithm for solving linear and nonlinear problems; (b) it does not involve any artificial parameters and additional variables, such as the Lagrange multipliers; (c) The identical effective stiffness matrices can be obtained inside two sub-steps; (d) it is a self-starting algorithm. Some numerical experiments are given to show the superiority of the new algorithm and the Bathe algorithm over the dissipative CH-α algorithm and the non-dissipative trapezoidal rule. 相似文献
10.
Neculai Andrei 《Numerical Functional Analysis & Optimization》2019,40(13):1467-1488
A new diagonal quasi-Newton updating algorithm for unconstrained optimization is presented. The elements of the diagonal matrix approximating the Hessian are determined as scaled forward finite differences directional derivatives of the components of the gradient. Under mild classical assumptions, the convergence of the algorithm is proved to be linear. Numerical experiments with 80 unconstrained optimization test problems, of different structures and complexities, as well as five applications from MINPACK-2 collection, prove that the suggested algorithm is more efficient and more robust than the quasi-Newton diagonal algorithm retaining only the diagonal elements of the BFGS update, than the weak quasi-Newton diagonal algorithm, than the quasi-Cauchy diagonal algorithm, than the diagonal approximation of the Hessian by the least-change secant updating strategy and minimizing the trace of the matrix, than the Cauchy with Oren and Luenberger scaling algorithm in its complementary form (i.e. the Barzilai-Borwein algorithm), than the steepest descent algorithm, and than the classical BFGS algorithm. However, our algorithm is inferior to the limited memory BFGS algorithm (L-BFGS). 相似文献
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介绍了一种求解TSP问题的算法—改进的蚁群算法,算法通过模拟蚁群搜索食物的过程,可用于求解TSP问题,算法的主要特点是:正反馈、分布式计算、与某种启发式算法相结合.通过对传统蚁群算法的改进可以得到较好的结果.计算机仿真结果表明了该算法的有效性. 相似文献
12.
Hua-zhu Chen Jin-ping Song Xue-Cheng Tai 《Advances in Computational Mathematics》2009,31(1-3):115-130
We apply the dual algorithm of Chambolle for the minimization of the LLT model. A convergence theorem is given for the proposed algorithm. The algorithm overcomes the numerical difficulties related to the non-differentiability of the LLT model. The dual algorithm is faster than the original gradient descent algorithm. Numerical experiments are supplied to demonstrate the efficiency of the algorithm. 相似文献
13.
A rank-one algorithm is presented for unconstrained function minimization. The algorithm is a modified version of Davidon's variance algorithm and incorporates a limited line search. It is shown that the algorithm is a descent algorithm; for quadratic forms, it exhibits finite convergence, in certain cases. Numerical studies indicate that it is considerably superior to both the Davidon-Fletcher-Powell algorithm and the conjugate-gradient algorithm. 相似文献
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根据块三对角矩阵的特殊分解,给出了求解块三对角方程组的新算法.该算法含有可以选择的参数矩阵,适当选择这些参数矩阵,可以使得计算精度较著名的追赶法高,甚至当追赶法失效时,由该算法仍可得到一定精度的解. 相似文献
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A modified fixed-point iterative algorithm for image restoration using fourth-order PDE model 总被引:1,自引:0,他引:1
In this paper, we propose a modified fixed point iterative algorithm to solve the fourth-order PDE model for image restoration problem. Compared with the standard fixed point algorithm, the proposed algorithm needn?t to compute inverse matrices so that it can speed up the convergence and reduce the roundoff error. Furthermore, we prove the convergence of the proposed algorithm and give some experimental results to illustrate its effectiveness by comparing with the standard fixed point algorithm, the time marching algorithm and the split Bregman algorithm. 相似文献
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In this paper, we present a long-step primal path-following algorithm and prove its global convergence under usual assumptions. It is seen that the short-step algorithm is a special case of the long-step algorithm for a specific selection of the parameters and the initial solution. Our theoretical result indicates that the long-step algorithm is more flexible. Numerical results indicate that the long-step algorithm converges faster than the short-step algorithm. 相似文献
18.
P. P. B. Eggermont 《Applied Mathematics and Optimization》1999,39(1):75-91
We study a modification of the EMS algorithm in which each step of the EMS algorithm is preceded by a nonlinear smoothing
step of the form , where S is the smoothing operator of the EMS algorithm. In the context of positive integral equations (à la positron emission tomography)
the resulting algorithm is related to a convex minimization problem which always admits a unique smooth solution, in contrast
to the unmodified maximum likelihood setup. The new algorithm has slightly stronger monotonicity properties than the original
EM algorithm. This suggests that the modified EMS algorithm is actually an EM algorithm for the modified problem. The existence
of a smooth solution to the modified maximum likelihood problem and the monotonicity together imply the strong convergence
of the new algorithm. We also present some simulation results for the integral equation of stereology, which suggests that
the new algorithm behaves roughly like the EMS algorithm.
Accepted 1 April 1997 相似文献
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Antoine Jouglet Ceyda Oğuz Marc Sevaux 《Journal of Mathematical Modelling and Algorithms》2009,8(3):271-292
The paper considers the hybrid flow-shop scheduling problem with multiprocessor tasks. Motivated by the computational complexity
of the problem, we propose a memetic algorithm for this problem in the paper. We first describe the implementation details
of a genetic algorithm, which is used in the memetic algorithm. We then propose a constraint programming based branch-and-bound
algorithm to be employed as the local search engine of the memetic algorithm. Next, we present the new memetic algorithm.
We lastly explain the computational experiments carried out to evaluate the performance of three algorithms (genetic algorithm,
constraint programming based branch-and-bound algorithm, and memetic algorithm) in terms of both the quality of the solutions
produced and the efficiency. These results demonstrate that the memetic algorithm produces better quality solutions and that
it is very efficient. 相似文献