vector solution;
solution = solve_quadratic(0.5 * grav, -vz, zdist); // equation "z(ti) = zdist"
// ALWAYS solvable because jumpheight >= zdist
vector solution;
solution = solve_quadratic(0.5 * grav, -vz, zdist); // equation "z(ti) = zdist"
// ALWAYS solvable because jumpheight >= zdist