Warning !

Soas is no longer maintained. You are strongly encouraged to switch to its successor, QSoas

fit_arb: Fitting to a user-defined function.

Type fig_arb, and type in the function you want to use to fit the data. You may use certain constants in the formula, which are reminded:

The following constants are available
T : The absolute temperature
F : The faraday constant
f : F/RT
f(x) =exp(b*x + c*sqrt(x))

Soas detects automatically the unkown parameters in the expression. You can modify them as usual before the fit; this is actually recommended, as, unlike standard functions where Soas tries to provide sane default values for parameters, there is no way to do so for arbitrary functions.

The model function can call any of the following elementary functions: exp, ln, sin, cos, tan, sqrt, asin, acos, atan, cosh, sinh, tanh, erf, gamma, heavy. ``**'' is the symbol for exponentiation.

Christophe Leger 2009-02-24