W orking with a model

All differential equation models begin with a differential equation. If the problem is an intial value problem, an initial condition is also needed. Replace the question marks ( ? ) in the following input regions to define the relevant ODE model.

> MODEL := diff( ? , ? ) = ? ; # define the differential equation model

> IC := ? = ? ; # specify an initial condition

Replace the question marks ( ? ) in the following input regions to create the direction field for your model.

> VAR := { ? }; # specify the variables in the model

> DOMAIN := ? = ? .. ? ; # specify a reasonable interval for the independent variable

> RANGE := ? = ? .. ? ; # specify a reasonable interval for the dependent variable

> DEplot( MODEL, VAR, DOMAIN, RANGE, arrows = MEDIUM );

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Next plot one or more solution curves corresponding to the specified initial conditions.

> DEplot( MODEL, VAR, DOMAIN, [ [IC] ], linecolor = BLUE, arrows = MEDIUM );

> DEplot( MODEL, VAR, DOMAIN, [ [IC1], [IC2], [IC3] ], linecolor = [BLUE, GREEN, BLACK], arrows = MEDIUM );

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Look at the help under plot,options to see other ways you can customize your plots.

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