There are a few problems.
Problem 1:
for c = i
tells the loop to iterate once, with the value of c being i. I imagine you meant:
for c = 1:i
which tells the loop to iterate i times, with the c taking values starting with 1 and going to i.
Problem 2:
if ...
Ts = Ts1;
Tg = Tg1;
elseif ...
Ts = Ts2;
Tg = Tg2;
end
This overwrites Ts and Tg on each iteration, so after the loop, you only ever have the value from the last iteration (which are the entire Ts1/Tg1 or Ts2/Tg2 vectors).
Instead, take only the appropriate single element each iteration:
if ...
Ts(c) = Ts1(c);
Tg(c) = Tg1(c);
elseif ...
Ts(c) = Ts2(c);
Tg(c) = Tg2(c);
end
Problem 3:
if z(:,c)>=0 && z(:,c)<=0.32
% ...
elseif z(:,c)>0.32 && z(:,c)<=0.414
% ...
end
What happens if z(:,c)<0 or z(:,c)>0.414? Then neither of those conditions is true, so Ts and Tg do not get assigned to, so they have their value left over from the previous iteration, or they are undefined if this happens on the first iteration. As you said, there are two conditions ("z is less than or equal to 0.32 ... z is greater than 0.32"), so there is only one check necessary:
if z(:,c)<=0.32
% ...
else
% ...
end
Inefficiency (but not a problem in that it doesn't impact the result): You can calculate Ts1, Ts2, Tg1, Tg2 one time before the loop, rather than on each iteration of the loop, because these vectors contain the values for all elements of z, so they don't depend on the loop iterator variable c.
However, all that being said, you can replace your loop approach with a simple and efficient logical indexing approach:
z=linspace(0,0.407);
%explicit equations
Ts1 = ((-3508440.83).*(z.^5))+((3221859.34).*(z.^4))-((1089760.82).*(z.^3))+((165361.13).*(z.^2))-((12015.96).*z)+(1179.21);
Ts2 = ((-1906981.2).*(z.^3))+((2073664.15).*(z.^2))-((754331.65).*(z))+(92096.47);
Tg1 = ((2796881.8).*(z.^5))-((2553240.18).*(z.^4))+((852324.51).*(z.^3))-((124780.34).*(z.^2))+((6092.92).*(z))+(889.33);
Tg2 = ((-1567143.11).*(z.^3))+((1751141.7).*(z.^2))-((653704.46).*(z))+(81812.04);
Tg = NaN(size(Tg1)); % initialize Tg and Ts
Ts = NaN(size(Ts1));
idx = z <= 0.32; % idx is a vector of logicals (true/false) saying whether each element of z is <= 0.32
Tg(idx) = Tg1(idx); % take Tg1 when z <= 0.32
Ts(idx) = Ts1(idx); % take Ts1 when z <= 0.32
Tg(~idx) = Tg2(~idx); % take Tg2 when z > 0.32
Ts(~idx) = Ts2(~idx); % take Ts2 when z > 0.32
plot(z,Tg)
hold on
plot(z,Ts)
legend({'Gas' 'Solid'})
ylabel('T')
xlabel('z')
