Function SCIPintervalQuadUpperBound 

pub unsafe extern "C" fn SCIPintervalQuadUpperBound(
    infinity: f64,
    a: f64,
    b_: SCIP_INTERVAL,
    x: SCIP_INTERVAL,
) -> f64

computes exact upper bound on \f$ a x^2 + b x \f$ for x in [xlb, xub], b an interval, and a scalar

Uses Algorithm 2.2 from Domes and Neumaier: Constraint propagation on quadratic constraints (2008).