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as understood by Config::Tiny. (Should be self explanatory.)

=head1 EXAMPLES

=head2 Long Example

The following B<extensive> example comes with the distribution as "ex1.ini".
See below for a minimal working example.

    # This will be a one-dimensional harmonic oszillator (in 2D-space)
    
    # Number of dimensions in simulation (up to three dimensions allowed)
    dimensions = 2
    
    # Given a sufficiently fast cpu, you can have the simulation run very fast
    # by setting this to a high value. Setting it to one makes the simualtion
    # pause after integration steps so that the total speed is no greater
    # than realtime.
    timewarp = 1
    
    # The sensitivity of the integrator.
    # Smaller is more accurate but more cpu intensive.
    epsilon = 0.0000001
    
    # Set to a true value to have the particle traces stay on screen.
    # Note, however, that this tends to increase memory usage with time - slowly.
    # This option may be omitted and defaults to false.
    trace = 0
    
    # Set this to any HTML color to change the axis' color.
    # This option may be omitted and defaults to black.
    axiscolor = #222277
    
    # This sets the zoom. It may be omitted and defaults to 20 for
    # backwards compatibility.
    zoom = 60
    
    # The following options specify the base point and the plane vectors
    # for the viewing plane. (That's the plane you project the 3D coordinates on.)
    # Make sure your vectors are normalized because otherwise your display will
    # be stretched.
    # The values in this example are at the same time the default values.
    plane_base_x = 0
    plane_base_y = 0
    plane_base_z = 0
    
    plane_vec1_x = 0.371391
    plane_vec1_y = 0.928477
    plane_vec1_z = 0
    
    plane_vec2_x = 0.371391
    plane_vec2_y = 0
    plane_vec2_z = 0.928477
    
    # You may omit this option. If you don't, however, all 3D data will be written
    # to the specified file for further processing. (For example with
    # tk-motion-img.pl.)
    # output_file = ex1.dat
    
    # This section contains any number of constants that may be used in the
    # formulas that define the differential equations. The section should
    # exist, but it may be empty.
    [constants]
    k = 1
    m = 1
    
    # This section defines the movement of the first particle (p1).
    [p1]
    
    # This is the differential equation of the first coordinate of the
    # first particle. It is of the form
    #      (d^2/dt^2) x1 = yourformula
    # "yourformula" may be any string that is correctly parsed by the
    # Math::Symbolic parser. It may contain the constants specified above
    # and any of the following variables:
    # x1 is the first (hence "x") coordinate of the first particle (hence "x1").
    # x2 is the x-coordinate of the second particle if it exists, and so on.
    # y3 therefore represents the second coordinate of the third particle whereas
    # z8 is the third coordinate of the eigth particle.
    # Note that this example simulation only has two dimensions and hence
    # "z8" doesn't exist.
    # vx1 is the x-component of the velocity of the first particle.
    # Therefore, vy3 represents the y-component of the velocity of the
    # third particle. You get the general idea...
    # All formulas may be correlated with other differential equations.
    # That means, "funcx" of the first particle may contain y2 and the
    # like. (Provided the dimensions and the particles exist.)
    # 
    # Our example is a simple oszillator
    funcx = - k/m * x1*(x1^2)^0.5
    
    # Diff. eq. for the second coordinate of the first particle
    # We want a 1-dimensional oszillator, so we set this to zero.
    funcy = 0
    
    # Initial values for the coordinates and velocity of the first particle.
    x = 0
    y = -0.5
    vx = -20
    vy = 0
    
    # Color of the current location of the particle (default: white)
    # HTML-style colors.
    color = #FF0000
    # Color of the particle's trace if trace == 1 (default: black)
    colort = #880000
    
    # Other particles are defined in the same fashion.

=head2 Short Example

This example pretty much reproduces the extensive example above omitting
any options that aren't mandatory (or required to make the examples
the same).

    # This will be a one-dimensional harmonic oszillator (in 2D-space)
    
    dimensions = 2
    zoom = 60
    
    [constants]
    k = 1
    m = 1
    
    [p1]
    funcx = - k/m * x1*(x1^2)^0.5
    funcy = 0
    
    x = 0
    y = -0.5
    vx = -20
    vy = 0

=head1 METHODS

=head2 new

Returns a new App::Physics::ParticleMotion object.

=head2 config

Returns the current configuration as a Config::Tiny object. If a first argument
is passed, it is used as the new configuration. It may be either a Config::Tiny
object to replace the old one or the name of a file to read from.

=head2 run

Runs the application. Can't be called more than once.

=head1 SEE ALSO

New versions of this module can be found on http://steffen-mueller.net or CPAN.

L<Math::Symbolic> implements the formula parser, compiler and evaluator.
(See also L<Math::Symbolic::Parser> and L<Math::Symbolic::Compiler>.)

L<Config::Tiny> implements the configuration reader.

L<Tk> in conjunction with L<Tk::Cloth> offer the GUI.

L<Math::RungeKutta> implements the integrator.

L<Math::Project3D> projects the 3D data onto a viewing plane.

=head1 AUTHOR

Steffen Mueller, E<lt>particles-module at steffen-mueller dot net<gt>

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2004-2005 by Steffen Mueller

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.6.1 or,
at your option, any later version of Perl 5 you may have available.

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