LV Model Parameter Files

These are parameter files for various Lotka-Volterra systems:

paramsa.dat    N = 16    xmin > 1e-6    LE > 1e-3
paramsb.dat    N = 24    xmin > 1e-6    LE > 1e-3
paramsc.dat    N = 24    xmin > 1e-6    LE > 1e-3
paramsd.dat    N = 48    xmin > 1e-6    LE > 1e-3
paramse.dat    N = 48    xmin > 1e-6    LE > 1e-3
paramsf.dat    N = 48    xmin > 1e-6    LE > 1e-3    4 nearest neighbors in a ring
paramsg.dat    N = 64    xmin > 1e-6    LE > 1e-3
paramsh.dat    N = 25    xmin > 1e-6    LE > 1e-3    8 nearest neighbors on 5x5 grid
paramsi.dat    N = 100   xmin > 1e-6    LE > 1e-3
paramsj.dat    N = 64    xmin > 1e-6    LE > 1e-3    8 nearest neighbors on 8x8 grid
paramsk.dat    N = 100   xmin > 1e-6    LE > 1e-3    8 nearest neighbors on 10x10 grid
paramsl.dat    N = 100   xmin > 1e-6    LE > 1e-3    sparse matrix (many zero terms)
paramsm.dat    N = 100   xmin > 1e-6    LE > 1e-3    4 nearest neighbors in a ring
paramsn.dat    N = 144   xmin > 1e-6    LE > 1e-3    8 nearest neighbors on 12x12 grid
paramso.dat    N = 256   xmin > 1e-6    LE > 1e-3    8 nearest neighbors on 16x16 grid
paramsp.dat    N = 256   xmin > 1e-6    LE > 1e-3    4 nearest neighbors in a ring
paramsq.dat    N = 400   xmin > 1e-6    LE > 1e-3    8 nearest neighbors on 20x20 grid
paramsr.dat    N = 400   xmin > 1e-6    LE > 1e-3    4 nearest neighbors in a ring
paramss.dat    N = 144   xmin > 1e-6    LE > 1e-3
paramst.dat    N = 256   xmin > 1e-6    LE > 1e-3    sparse matrix (many zero terms)
paramsu.dat    N = 5     xmin > 1e-6    LE > 1e-3
paramsv.dat    N = 48    xmin > 1e-6    LE > 1e-3    4 nearest neighbors in a uniform ring
paramsw.dat    N = 100   xmin > 1e-6    LE > 1e-3    4 nearest neighbors in a uniform ring
paramsx.dat    N = 100   xmin > 1e-6    LE > 1e-3    3 nearest neighbors in a uniform ring
paramsy.dat    N = 100   xmin > 1e-6    LE > 4e-3    4 nearest neighbors in a uniform ring
paramsz.dat    N = 100   xmin > 1e-6    LE > 1e-3    2 (of 4) nearest neighbors in a uniform ring

params1.dat N = 100 xmin > 1e-6 LE > 1e-3 10 (of 24) nearest neighbors on 10x10 uniform grid

Format for the above files:

Seed for random number generator
N (number of species)
xo(i) (initial conditions, N values)
r(i) (growth rates, N values)
a(i,j) (matrix of interations, N*N values)
x(i) (final conditions, N values)
LE (Lyapunov exponent)

Program details:

These parameter files were generated with variants of the program evolve.exe whose source code is at evolve.bas. You can examine any of the cases by launching the program with a command line trailer, such as "evolve paramsa.dat".

The algorithm that produced the above files is as follow: