Documentation


Model.addGenConstrPoly()

addGenConstrPoly ( xvar, yvar, p, name="", options="" )

Add a new general constraint of type GRB.GENCONSTR_POLY to a model.

A polynomial function constraint states that the relationship <span>$</span>y = p_0 x^d + p_1 x^{d-1} + ... + p_{d-1} x + p_{d}<span>$</span> should hold between variables <span>$</span>x<span>$</span> and <span>$</span>y<span>$</span>.

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, FuncPiecesLength, and FuncPieceRatio. For details, consult the General Constraint discussion.

Arguments:

xvar (Var): The <span>$</span>x<span>$</span> variable.

yvar (Var): The <span>$</span>y<span>$</span> variable.

p: The coefficients for the polynomial function (starting with the coefficient for the highest power).

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 = 2 x^3 + 1.5 x^2 + 1
  gc = model.addGenConstrPoly(x, y, [2, 1.5, 0, 1])