i have some problems of my ode45 code !!

(sorry about my english skill)

first, this is rocket.m file

function dH=rocket(t,H)
global km mildo press temp;
m = 6100;   % kg
a = 0.8;     % m^2
ve = 2060.1; % m/s
thrust = 13000*9.81; 
pe = thrust/a;  
dmdt = -(thrust)/ve;
rho = 1;
pa = 1;
tem = 1;
%M = (331.5+(0.6*tem));      
veeff = ve-a*(pe-pa)/dmdt;  % ve.eff
%v = ; 
cd = 1;
dH(1,1) = H(2);
dH(2,1) = cd*rho(1)*a*H(1)^2-dmdt*ve;

and this is rocket_test.m file

[t H] = ode45(@(t,H)rocket(t,H),[0 10],[0 0]);
H1=H(:,1);
H2=H(:,2);
plot(t,H1,t,H2)
legend('height','vel')
set(gca,'fontsize',20)

when i run rocket_test.m code, the error massage is

Warning: Failure at t=1.930812e-01.  Unable to meet integration tolerances without
reducing the step size below the smallest value allowed (4.440892e-16) at time t. 
> In ode45 (line 308)
  In rocket_test (line 2)

and when i change &nbsp dH(2,1)=cd*rho(1)*a*H(1)^2-dmdt*ve; &nbsp to &nbsp dH(2,1)=cd*rho(1)*a*H(1)-dmdt*ve; at rocket.m file, it works.

so i think H(1) ^2 the square is the problem.

but when i test below code, it works.

function dH=rocket(t,H)
dH(1,1) = H(2);
dH(2,1) = H(1)^2;

i can't find what is the problems..........

Answer 1

[Star Strider]

When ode45 has problems, try ode15s. It may succeed where ode45 does not.

[kyu hong lee]

ode15s doesnt work too... T_T