Swifter — an improved solar system integration software package

This project is supported by NASA's Applied Information Systems Research Program (AISRP)

The Swifter software package, written by David E. Kaufmann, is a completely redesigned and improved version of the Swift package of Hal Levison and Martin Duncan. Like Swift, Swifter is designed to integrate a set of mutually gravitationally interacting bodies together with a group of massless test particles that feel the gravitational influence of the massive bodies but do not affect each other or the massive bodies. In addition, the SyMBA integrator supports a second class of massive bodies whose masses are less than some user-specified value. These bodies gravitationally interact with the more massive bodies, but do not interact with each other. Seven integration techniques are included in the current beta release of Swifter:

Wisdom-Holman Mapping¹ (WHM). This algorithm was created by Jack Wisdom and Matt Holman (1991; AJ, 102, 1528).
Regularized Mixed Variable Symplectic (RMVS) method. This is an extension of WHM that handles close approaches between test particles and planets. This algorithm was created by Hal Levison and Martin Duncan (1994; Icarus, 108, 18).
Democratic Heliocentric (DH, or HELIO) method. This is a basic (i.e., no close approaches) symplectic integrator that uses democratic heliocentric coordinates. This method is described by Duncan, Levison, and Lee (1998; AJ, 116, 2067).
Symplectic Massive Body Algorithm (SyMBA). This is an extension of HELIO that handles close approaches between planets and any of the other objects in the simulation. This algorithm is described in the Duncan, Levison, and Lee (1998) reference given above. See also Levison and Duncan (2000; AJ, 120, 2117).
A fourth-order T+U Symplectic (TU4) method. This algorithm was created by Jeff Candy and W. Rozmus (1991; J. Comp. Phys., 92, 230). Also see Gladman, Duncan, and Candy (1991; CeMDA, 52, 221).
A nonsymplectic fifteenth-order integrator that uses Gauss-Radau spacings (RADAU15, or RA15). This algorithm is described by Everhart (1985; ASSL Vol. 115: IAU Colloq. 83: Dynamics of Comets: Their Origin and Evolution, 185).
A Bulirsch-Stoer (BS) method. See, for example, Section 16.4 of Press, Teukolsky, Vetterling, and Flannery (1992; Numerical Recipes in Fortran 77, 718).

Swifter is designed so that the calls to each of these integrators look similar, thereby facilitating the replacement of one with another.

Swifter should compile and run on any UNIX or Linux machine that has ANSI standard Fortran 90/95 and C compilers. Please contact the author if you have any problems or are seeking to build Swifter on a different platform.

You can get a gzipped tar file of Swifter by clicking here. Uncompress and un-tar the file in the location where you wish to create the top-level "swifter" directory by entering the following commands:

Now continue by reading the README.swifter file located in the top-level "swifter" directory.

¹ This algorithm was known as MVS in early releases of Swift.

This site created and maintained by David E. Kaufmann