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Model.addGenConstrLogA()
addGenConstrLogA ( xvar, yvar, a, name="", options="" )
Add a new general constraint of type GRB.GENCONSTR_LOGA to a model.
A logarithmic function constraint states that the relationship
should hold for variables 
and 
, where 
is the (constant) base.
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
Arguments:
xvar (Var): The variable.
yvar (Var): The variable.
a (float): The base of the function, .
name (string, optional): Name for the new general constraint.
options (string, optional): A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. "FuncPieces=-1 FuncPieceError=0.001").
Return value:
New general constraint.
Example usage:
# y = log10(x) gc = model.addGenConstrLogA(x, y, 10.0, "log10", "FuncPieces=-1 FuncPieceError=1e-5")
