Query a single value from a double-valued array attribute.
A non-zero return value indicates that a problem occurred while querying the attribute. Refer to the Error Code table for a list of possible return values. Details on the error can be obtained by calling GRBgeterrormsg.
model: A loaded optimization model, typically created by routine GRBnewmodel or GRBreadmodel.
attrname: The name of a double-valued array attribute. Available attributes are listed and described in the Attributes section of this document.
element: The index of the requested array element.
values: A pointer to the location where the requested value should be returned.
Note that this method should be used for array attributes only (i.e., variable or constraint attributes). To query a scalar attribute (i.e., a model attribute), use GRBgetdblattr instead.
double first_one; error = GRBgetdblattrelement(model, "X", 0, &first_one);