All these routines are made available with no warranty whatsoever---use them at your own risk.
  • SCILAB function contour3d to draw isosurfaces of a function of space (three variables). Analogous to contour2d. Download contour3d.sci and two examples of its use in testiso.sci
  • MATLAB functions to numerically solve differential-algebraic equations (DAEs): get all the following and some limited explanation by downloading dae.dtx and running it through LaTeX. It contains:
    • a general purpose second-order function, dae2.m,
    • a cheap fourth-order function, dae4.m (but for which neutral oscillations and waves are numerically unstable),
    • and a fourth-order function, dae4o.m good for dynamics with neutral oscillations and waves.
    An example of their use to simulate the motion of a pendulum using equations in Cartesian variables is executed by the main program pendrun.m and uses the equations coded in penddae.m and the graphical output of pendg.m. Try it.

  • I also have two MATLAB functions to numerically integrate stochastic differential equations (SDEs): sde1.m integrates an SDE that has only one noise source; whereas sde1m.m integrates an sde with multiple noise sources.

    These routines are only first order accurate because it is a cow of a job to write higher order accurate routines to provide strong solutions to the SDE.

  • fdim.sh a short MATLAB script to compute generalised dimensions and f(alpha) curve of a fractal or multi-fractal distribution.

    There are six files packed together using the Unix shar utility: five are functions used to compute the generalised dimensions and the f(alpha) curve; the sixth (eg.m) is an example script to check that it works. This is an early release of what I have found to be a robust algorithm, I welcome comments.