Pressure calculation loop error

I have to calculate the pressure at different altitudes. I have the code that calculate all of the variables to go into my pressure calculation and all of those run fine and seem to produce the values that I am looking for but when I try to run the pressure loop it says the sides have different values. Can anyone tell me where I am going wrong?

This is what I have so far:

clc;
clear all;

p(1)=1.013e5;
r=287;                               %Jules/kg*K
dz=200;

% =================== Gravity Calculations ============================

alt=0:200:50000;
Re=6.37e6;
g0=9.80665;
i=1:length(alt);
g=g0*((Re^2)./((alt(i)+Re).^2));


% =================== Temperature Calculations ============================

for i=1:length(alt)
    if alt(i)<=11000
        t(i)=((-71.5/11000).*alt(i)+15)+273;
    elseif 11000<alt(i) && alt(i)<=20100
        t(i)=(-56.5)+273;
    elseif 20100<alt(i) && alt(i)<=32200
        t(i)=((12/12100).*alt(i)-76.434)+273;
    elseif 32200<alt(i) && alt(i)<=47300
        t(i)=((42/15100).*alt(i)-134.063)+273;
    else
        t(i)=(-2.5)+273;
    end
    
    x=g./(r*t(i));
     
end

for i=1:length(alt)
    p(i+1)=p(i).*((1/2)*x.*dz)+(1-(1/2)*x.*dz);
end

[Geoff Hayes]

John - x is a 1x251 array, so the line of code

p(i+1)=p(i).*((1/2)*x.*dz)+(1-(1/2)*x.*dz);

is trying to assign a 1x251 array on the right-hand side to the 1x1 scalar on the left-hand side. Is this what you want, or do you mean to use the ith element of x in the calculation. SImilarly, in your for loop, you have

x=g./(r*t(i));

where g is the 1x251 array. Do you mean for x to be a 1x251 array where each element of this array changes on every iteration? Or should this be

x(i) = g(i)./(r*t(i));

?

[KSSV]

You should replace the last loop to this:

for i=1:length(alt)-1
    p(i+1)=p(i).*((1/2)*x(i)*dz)+(1-(1/2)*x(i)*dz);
end

[John Woods]

I tried your way KSSV but it still gave me an "Unable to perform assignment because the left and right sides have a

different number of elements." Error. Geoff, I am trying to get the code to calculate the pressure at each itteration of the altitude. All the other sections of the code are giving me the values that I am looking for so unless they are messing up my pressure calculations, I'd like to leave them how they are.

[KSSV]

If you replace the loop with the given..I am not getting any error.....your error is becuse you are using x, replace ot with x(i).

[John Woods]

Oh okay I just changed the for line. I got it now. Thank you so much!