I have this small extract of code from a book I have. But I don't really understand what is going on here. Is t0 and t1 given values in this code, even though Quadratic does not return anything (its a bool)?
// Solve quadratic equation for _t_ values
float t0, t1;
if (!Quadratic(A, B, C, &t0, &t1))
// Compute intersection distance along ray
if (t0 > ray.maxt || t1 < ray.mint)