NAME

       model-builder - graphical ODE simulator

DESCRIPTION

        Model Builder is a graphical ODE simulator.  It allows the user to
        define, simulate and analyze arbitrary systems of Ordinary Diferential
        Equations.

Features

       * Equation-based model definition. No need to learn to program to
         define and run your models. Just type-in you differential equations

       * Graphic output of simulation. You can save the graphics in the most
         common formats: png, svg, pdf, etc.

       * Spreadsheet view of the results. From the spreadsheet you can make
         customized plots from your variables. You can also export your data
         to a .csv text file

       * Latex rendering of your system of equations. Check you equation in
         clear mathematical notation.

       * Intuitive graphical interface.

       * Uncertainty analysis module. Implements a straightforward interface
         for the Bayesian Melding method.

       * Sensitivity analysis. Find out how sensitive your model is to
         variations in parameter values.

GETTING STARTED

        The best way to get started with ModelBuilder is open one of the
        models included with the distribution and look at it . Yes, it's that
        simple.

        So, if you have already intalled it, start Model-Builder by typing in
        the console:

        $ PyMB followed by <enter>.

        This will start Model-Buider . From now on I will assume that you
        know what a system of differential equations is, otherwise you
        probably should not be using Model-Builder.

        The larger box on the main frame, labeled "Differential Equations" is
        where we are going to start. On this text box you will write your
        system of equations (or a single equation) The syntax is that of
        python for mathematical expressions and functions and there are some
        conventions also, which I will explain below:

       * First of all, Model-Builder expects only the right-hand-side (RHS)
         of you equations to be present one per line in the equations
         box. The LHS is assumed to be of the form dy(t)/dt, dy_i/dt where i
         is an index to the the number of equations in your model. This
         number i will be used to refer to the state variables of the model (
         y[i] ). This index, i, MUST start at 0, so if your model has 3
         equations, their state variables will be y[0], y[1], and y[2] .

       * Another convention is the reference to model parameters. Any number
         of parameters may be included in the equations by the using this
         nomeclature: p[0], p[1], and so on. These parameter must the be
         specified one per line and in ascending order in the "Parameters"
         box. So the first line would be the definition of p[0], the second
         of p[1] and so forth.

       * The mathematical expressions that make up the equations and the
         parameters may include any function of the numpy python module. This
         allows for the easy contruction of models with a level of
         sophistication higher than that of a simple algebraic
         expression. Time may be referenced in the equations or parameter
         expressions by the variable "t". So if you want a parameter that is
         a function of time, you can simply write in the parameter box.

       * The user familiar with python will also be able to include more
         advanced structures in the model specification, such as Lambda
         functions for instance.

         Well, with that out of the way, it remains to explain the rest of
         the interface which is pretty much self-explanatory:

       * The initial values box should include one number for each equation
         (line) in the equations box. The numbers should be separated by
         spaces.

       * The start time is the time value at which the equations begin to be
         evaluated. The values of the state variables at this point in time
         are those specified in the initial conditions.

       * End time: You can figure this one out...

       * Time step: this is the time-step used in reporting the output of the
         simulation. The actual time step used by the numeric integrator is
         variable and chosen on the fly. Its normally much finer that what
         you specify here.

       * Critical time steps. Most user wil leave this box empty.

       * First Step: The size of the first step. Leave at 0 for automatic
         determination.

       * Min Step Size and Max Step Size: Respectively the minimum and
         maximum value for step sizes as chosen by variable step size
         algorithm. Leave at zero for automatic determination.

       * Full Output check box: If this box is checked a lot of useful
         information about the integration is included in the output. Check
         out the output spreadsheet to see what they are.

       * Show convergence message: if this box is checked, ModelBuilder will
         print "Integration successful" to the console after the integration
         is completed. Useful for debugging purposes only. Uncheck if you are
         doing uncertainty analyses. as it will slow things down.

       * Once you are done entering the necessary information for you model,
         Just press the start button to calculate your model. Enjoy!

HOMEPAGE

       http://model-builder.sourceforge.net/

AUTHOR

        This manual page was written by Varun Hiremath
        <varunhiremath@gmail.com>, for the Debian project (but may be used by
        others).

                                         December 4, 2006                        model-builder(1)