Description Usage Arguments Details Value Note Author(s) References See Also Examples

Gives the value of the right side of a first order Ordinary Differential Equation Used in frunge (Numeric resolution using Runge-Kutta 4 metthod)

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`t` |
time, independent variable |

`y` |
values of the unknown function at t |

`param` |
numeric vector : the set of parameters defining the function |

the unique expression composing the body of dfdt is intended as the right side of the first order
differential equation :

*
dy/dt = dfdt(t,y,param)*

The function body has to be written by the user.

param must take the form c(param1,param2,param3).
if the initial value (y0) is used as a parameter (for model fitting for instance), it **must be the last**
in the list and **not used** in dfdt.

a single float numeric value : the derivative of the unknown function at time t.

When used as argument for frunge, the initial condition **y0** may be used as a parameter subject to fitting by `nls`

, for instance. In this condition, **y0** must appear as the **last** parameter in param and **must not** be used nor modified in `dfdt`

Jean-Sebastien Pierre

[email protected]

Any textbook in mathematics

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