Function SCIPevalExpr 

pub unsafe extern "C" fn SCIPevalExpr(
    scip: *mut SCIP,
    expr: *mut SCIP_EXPR,
    sol: *mut SCIP_SOL,
    soltag: c_longlong,
) -> SCIP_RETCODE

evaluate an expression in a point

Iterates over expressions to also evaluate children, if necessary. Value can be received via SCIPexprGetEvalValue(). If an evaluation error (division by zero, …) occurs, this value will be set to SCIP_INVALID.

If a nonzero \p soltag is passed, then only (sub)expressions are reevaluated that have a different solution tag. If a soltag of 0 is passed, then subexpressions are always reevaluated. The tag is stored together with the value and can be received via SCIPexprGetEvalTag().