Now showing items 1-10 of 27
ønix: A Unix Emulator for VAX/VMS
A Variable-Metric Variant of the Karmarkar Algorithm for Linear Programming
The most time-consuming part of the Karmarkar algorithm for linear programming is computation of the step direction, which requires the projection of a vector onto the nullspace of a matrix that changes at each iteration. ...
Simultaneous Determination of Source Wavelet and Velocity Profile Using Impulsive Point-Source Reflections from a Layered Fluid
The determination of source signature is a major calibration problem in reflection seismology. This "deconvolution" problem is conventionally approached by way of statistical methods, by direct measurement, or by the ...
Safeguarding Hessian Approximations in Trust Region Algorithms
In establishing global convergence results for trust region algorithms applied to unconstrained optimization, it is customary to assume either a uniform upper bound on the sequence of Hessian approximations or an upper ...
Domain Decomposition and Mixed Finite Element Methods for Elliptic Problems
In this paper we describe the numerical solution of elliptic problems with nonconstant coefficients by domain decomposition methods based on a mixed formulation and mixed finite element approximations. Two families of ...
A Convergence Theory for the Structured BFGS Secant Method with an Application to Nonlinear Least Squares
In 1981, Dennis and Walker developed a convergence theory for structured secant methods which included the PSB and the DFP secant methods, but not the straightforward structured version of the BFGS secant method. Here we ...
A Parametric Study of Viscous Fingering in Miscible Displacement by Numerical Simulation
Numerical simulation is used to study the effects of several parameters on miscible viscous fingering. A miscible flood of a rectangular slab is simulated in two spatial dimensions. The parameters, obtained by the ...
Projected Newton for the Symmetric Eigenvalue Problem has Order 1+sqrt(2)
In their study of the classical inverse iteration algorithm, Peters and Wilkinson considered the closely related algorithm that consists of applying Newton's method, followed by a 2-norm normalization, to the nonlinear ...
Domain Decomposition for Elliptic Partial Differential Equations with Neumann Boundary Conditions
Discretization of a self-adjoint elliptic partial differential equation by finite differences or finite elements yields a large, sparse, symmetric system of equations, Ax=b. We use the preconditioned conjugate gradient method with domain decomposition to develop an effective, vectorizable preconditioner which is suitable for solving large two-dimensional problems on vector and parallel machines....