Function SCIPisUpdateUnreliable 

pub unsafe extern "C" fn SCIPisUpdateUnreliable(
    scip: *mut SCIP,
    newvalue: f64,
    oldvalue: f64,
) -> c_uint

Checks if an iteratively updated value is reliable or should be recomputed from scratch. This is useful, if the value, e.g., the activity of a linear constraint or the pseudo objective value, gets a high absolute value during the optimization process which is later reduced significantly. In this case, the last digits were canceled out when increasing the value and are random after decreasing it. We do not consider the cancellations which can occur during increasing the absolute value because they just cannot be expressed using fixed precision floating point arithmetic, anymore. In order to get more reliable values, the idea is to always store the last reliable value, where increasing the absolute of the value is viewed as preserving reliability. Then, after each update, the new absolute value can be compared against the last reliable one with this method, checking whether it was decreased by a factor of at least “lp/recompfac” and should be recomputed.