# How do I store values from a while loop and plot the values in fonction of the number of iteration?

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Sarah Mignon on 15 Oct 2020
Commented: Sarah Mignon on 15 Oct 2020
Hello!
In the loop while I would like to store the values of each loop, and plot it with the corresponding iteration t.
m_cafe=0.2; %kg
m_cream=0.05; %kg
Cp_water=4179,6;
T_cafe=5+273.15; %K
T_cream=90+273.15;
m_mix=m_cafe+m_cream;
Tm=(m_cafe*Cp_water*T_cafe+m_cream*Cp_water*T_cream)/(m_mix);
U=20; %W/m2.K
Tamb=20+273.15; %K
d=0.05; %m
r=d/2; %m
Vol_cafe=m_cafe*0.001 % 1 kg=1 liter= 0.001m3
Vol_mix=m_mix*0.001 %
h_cafe=Vol_cafe/(3.14*r^2)
h_mix=Vol_mix/(3.14*r^2)
Air_cafe=3.14*d*h_cafe
Air_mix=3.14*d*h_mix
step=0.5;
e=1
t=0
while e>=0.01
y=(Tm-Tamb)*exp(((-Air_mix*U)/(m_mix*Cp_water))*t)+Tamb;
Temp(t)=y;
e=abs(Temp-Tamb);
t=t+step
end
plot (t,Temp,'r')
##### 1 CommentShowHide None
Rik on 15 Oct 2020
This time I edited your question for you. Next time, please use the tools explained on this page to make your question more readable.

Rik on 15 Oct 2020
Indices in Matlab need to be positive integers. You should create a separate time vector.
And don't forget to index Temp, otherwise your condition will be a vector.
Sarah Mignon on 15 Oct 2020
Thank you for your help, I made it working

R2019a

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