Function SCIPchgVarLb 

pub unsafe extern "C" fn SCIPchgVarLb(
    scip: *mut SCIP,
    var: *mut SCIP_VAR,
    newbound: f64,
) -> SCIP_RETCODE

depending on SCIP’s stage, changes lower bound of variable in the problem, in preprocessing, or in current node; if possible, adjusts bound to integral value; doesn’t store any inference information in the bound change, such that in conflict analysis, this change is treated like a branching decision

@warning If SCIP is in presolving stage, it can happen that the internal variable array (which can be accessed via SCIPgetVars()) gets re-sorted.

@return \ref SCIP_OKAY is returned if everything worked. Otherwise a suitable error code is passed. See \ref SCIP_Retcode “SCIP_RETCODE” for a complete list of error codes.

@pre This method can be called if @p scip is in one of the following stages: - \ref SCIP_STAGE_PROBLEM - \ref SCIP_STAGE_TRANSFORMING - \ref SCIP_STAGE_PRESOLVING - \ref SCIP_STAGE_SOLVING

@note During presolving, an integer variable whose bound changes to {0,1} is upgraded to a binary variable.