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To specify custom fit function formula, press Add
button and select Custom Equation
in popup menu.
Enter your formula in y(x)=
text field below. Use x
as fit function argument. See formula syntax.
You may recall last entered custom fit functions using Recently Used Custom
item in Add
popup menu.
You can introduce fit function parameters with any names (except argument x
, and constants like e
, pi
, etc, full list: predefined constants):
a
and A
are different parameters)._
sign. You can use numbers in the middle or in the end of the name: a1, a_1, A1, a1t
, but the names like 1a
are not allowed.The parameters you introduce will automatically and immediately occur in parameters list, you do not need to enter parameters names in the list manually.
Random values are used as the initial values of parameters. Do not forget to set more relevant initial values, otherwise fit algorithm may fail.