# I want the graph of the function only show the part where x>0

3 views (last 30 days)
Phong Do on 12 Jan 2021
Commented: Phong Do on 13 Jan 2021
I can't find any command that allows me to plot the function only in the interval [0 inf]
Here's my code, can you help me please
syms t positive rational
disp ('Choose upward direction as positive direction');
disp ('Choose ground as the origin of coordinates');
fprintf ('The Newton''s second law equation for rocket motion: ');
disp ('m*dv/dt = -v0*dm/dt - mg');
k = input('Input the fuel combustion speed dm/dt = ');
m0 = input('The rocket''s mass m0 = ');
y0 = input('The rocket''s initial position y0 = ');
v0 = input('The rocket''s gas propulsion speed v0 = ');
g = 9.81;
v = v0*log(m0/(m0-k*t))-g*t;
a = diff(v,t);
fprintf ('The rocket''s acceleration: a = ');
disp (a);
y = y0 + int(v,0,t);
fprintf ('the equation of rocket motion : y =');
disp (y);
fplot(y);
title('Graph of the motion''s equation');
xlabel('Time t');
ylabel('Position y');
grid on;

Daniel Pollard on 12 Jan 2021
You want xlim. Give it one limit and it can calculate the other, or use
xlim(0, length(y)).
Phong Do on 13 Jan 2021
Can you be more specific?
I put that line under the "fplot(y)" and then it occured the error
Error using xlim (line 31)
When 2 input arguments are specified, the first argument must be an axes.