Why is the set of numbers p2 not showing up on my graph

[dpb]

Quite possible the values are nan from the looks of the equations, but since you posted as an image instead of text, it would take retyping everything over to do anything specific.

Try

figure
semilogx(h,p1)
yyaxis right
semilogx(h,p2)

and you'll see the value for p2 is quite small and goes to zero quickly.

[min(p2) max(p2)]

Answer 1

[Alan Stevens]

Should it be more like this? (Though I don't recognize the value you have for the gas constant; and temperature would normally be in K, whereas yours looks like C - perhaps 250K is appropriate for high up in the atmosphere. However, you haven't supplied the units, so it's difficult to tell!).

G0 = 9.80665;
R = 287.053;  % ?
p0 = 101325;
RE = 6371000;
T = 250;      % ?

h = linspace(0,100);

p1 = p0*exp(-G0*h*1000./(R*T));
p2 = p0*exp(-G0*RE*RE*h*1000./(RE + h*1000).^2/(R*T));

semilogx(p1,h,p2,h), grid
xlabel('pressure (pa)')
ylabel('altitude [km)')
legend('constant gravity','variable gravity')