[General Information]

Function Name=Logistic	; name show up in the select function dialog
Brief Description=Logistic dose response in Pharmacology/Chemistry
Function Type=Built-in		; source type, built-in, user-defined, external dll
Function Form=Expression	; function form;
Function Source=fgroup.Logistic
Number Of Parameters=4
Number Of Independent Variables=1
Number Of Dependent Variables=1


[Fitting Parameters]

Naming Method=user-defined
Names=A1,A2,x0,p
Lower bounds=--,--,--,0.0(X,ON)
Upper bounds=--,--,--,--
Meanings=init value,final value,center,power


[Independent Variables]

x = 


[Dependent Variables]

y = 


[Constants]


[Formula]
y = A2 + (A1-A2)/(1 + (x/x0)^p)

[Constraints]


[Parameters Initialization]
sort(x_y_curve);
//smooth(x_y_curve, 2);
x0 = xaty50( x_y_curve );
p = 3.0;
if( yatxmin( x_y_curve ) > yatxmax( x_y_curve ) )
{
  A1 = max( y_data );
  A2 = min( y_data );
}
else
{
  A1 = min( y_data );
  A2 = max( y_data );
}


[Initializations]


[After fitting]


[Controls]
General Linear Constraints=Off
Initialization scripts=Off
Scripts After fitting=Off


[Derived Parameters]
EC20 = 10^(log(x0) + log(0.25)/p);
EC50 = x0;
EC80 = 10^(log(x0) + log(4)/p);
