# MATLAB: Identify time and position when reach terminal velocity

numerical integrationode'sode45terminal velocity

hi, i have this code:
``F = 4000.0;            % forcem = 1300.0;            % massA = 3.0;               % frontal area,     [m^2]Cd = 0.6;              % drag coefficient, [-]rho = 1.23;          %air density v0 = 5;              %velocity at t = x = 0vTerm = sqrt(2*F/(Cd*rho*A));        %terminal velocity dxdt = @(t,x)(sqrt((2.*F)./(Cd.*rho.*A)));  % V(t) = diff( X(t) ,t )tspan =[0 100]; %x0 = 0;opts = odeset('RelTol',1e-8,'AbsTol',1e-8);[t,x] = ode45(dxdt, tspan, x0,opts);``
first i need to set the relative tolerance to 1e-8 by using odeset before using ode45 to solve for x and t, which i'm unfamiliar with so can i get some comment on what i did whether its right or not ??, if not, any suggestion would be appreciated, thanks.
secondly, i now need to find t and x at which the velocity reach 99% of vTerm and i got no where trying to solve it. i think one of the problem could be that my function was wrong since i dont think its return the v0=5 as in the question, but i cant seem to find another function for it. Can i please have some help, thank you