Name of program: simplex 4.0.1

Type of program: 3D inversion of geodetic data for displacement on faults.

Authors: G. A. Lyzenga, W. Panero, J. W. Parker

Institution: Harvey Mudd College / JPL-NASA

Program's heritage (ie name and author of predecesor code if any): Originally developed circa 1995 at Harvey Mudd College by combining two ancestor codes: (a) the "disloc" elastic half-space dislocation code of A. Donnellan and (b) the downhill simplex/simulated annealing algorithm published by Press et al. in Numerical Recipes in C.

Actively being further developed (y/n): y

Language: C

2d (y/n): can be used this way

3d (y/n): y

Elastic full space (y/n): n

Elastic half space (y/n): y

Layered elastic (y/n): n

Viscoelastic half space (y/n): n

Layered viscoelastic (y/n): n

Maximum number of faults: no maximum if recompiled

Foward model (y/n): n

Inversion capability (y/n): y

Type of inversion: downhill simplex / simulated anneal

Finite element ability (y/n): n

Boundary constraints: none

Automatic mesh generation: for output

Includes self gravitation (y/n): n

Quasi-static failure criteria (y/n): n

User defined failure criteria (y/n): n

Hardwired failure criteria (eg Coulomb, Rate & State): n

Dynamic solution (y/n): n

Includes waves (y/n): n

Highest resolved frequency: n/a

Includes inertia (y/n): n

Are there accompanying utilities (y/n): not at this time

Is it one main program or several programs that communicate via scripts, files, and pipes? One program.

If it is several programs, please give a 1 line description of the major players.

Input format description: text input describing model fault parameters and dependencies, as well as input observation data

Output format description: both interactive terminal output and text file

Is this code available to interested researchers (y/n): y

Executable available (y/n): for some systems

Type of machine: HPUX, other unix

Source available (y/n): y

Please describe what you consider to be the important features of this code in a paragraph or two.

The code is useful for inversion of 3-d geodetic data, including both GPS and SAR, for fault or effective fault elastic dislocation parameters. Interactive "exploratory" mode of operation facilitates work on marginally constrained or poorly determined problems, as well as the more robust situations handled by more traditional inversion methods.