Function SCIPcheckExprQuadratic 

pub unsafe extern "C" fn SCIPcheckExprQuadratic(
    scip: *mut SCIP,
    expr: *mut SCIP_EXPR,
    isquadratic: *mut c_uint,
) -> SCIP_RETCODE

checks whether an expression is quadratic

An expression is quadratic if it is either a square (of some expression), a product (of two expressions), or a sum of terms where at least one is a square or a product.

Use SCIPexprGetQuadraticData() to get data about the representation as quadratic.