plot inside loop!!!

beho86 · #1 (**permalink**) 07-02-2010, 09:33 PM

Hey guys,
I have a question: problem statement is:
Use Euler's method, and assume a cooling constant r = 0.2 , initial temperature of 86 C, and room temperature at 17 C. Choose your time
step h judiciously and integrate to 5 minutes.

You can add some cream which will drop the temperature instantly by 5 C.
(a) Now, add the cream at the beginning. Plot your results. What is the temperature after 5 min?
(b) Add the cream at the end. Plot the results (preferably on the same figure). What is the temperature at the end?

كود:

r=0.2; %Cooling Constant T=86 ; % Initial Temperature t=0 ; Ts=17; %Surrounding Temperature h=0.1 ; %Step Size nsteps=300 ; for i=0:nsteps fprintf('%0.2f %0.3f\n',t,T) dT=-r*h*(T-Ts) ; T=T+dT ; t=t+h; end plot(t,T)
I need to store the variables into an array, so that I can print it out, not just the last point of the loop.

second: if I want to add cream at the beginning: I need to subtract 5 from the second element.

Third: if I want to add cream at the end: I need to subtract 5 from the last element.

Abdurauf · 07-02-2010, 11:24 PM

r=0.2; %Cooling Constant
T=86 ; % Initial Temperature
t=0 ;
Ts=17; %Surrounding Temperature
h=0.1 ; %Step Size
nsteps=300 ;

for i=0:nsteps
fprintf('%0.2f %0.3f\n',t,T)
dT=-r*h*(T(i+1)-Ts) ;
T(i+2)=T(i+1)+dT ;
t(i+2)=t(i+1)+h;
end
plot(t,T)
t
T

beho86 · 07-02-2010, 11:32 PM

Hello Abdurauf,
It worked well, I just made a small change, in the print statement:

كود:

r=0.2; T=86 ; t=0 ; Ts=17; h=0.1 ; nsteps=3000 ; for i=0:nsteps dT=-r*h*(T(i+1)-Ts) ; T(i+2)=T(i+1)+dT ; t(i+2)=t(i+1)+h; fprintf('%0.2f %0.3f\n',t(i+1),T(i+1)) end plot(t,T)
Now, how the program will differs, when I add the cream at the beginning or at the end of the 5 min?!
Beginning, I should subtract 5 from the first cell, and update the rest of the cells.
End, subtract 5 from the last cell only.

Thanks so much for your help

أسماء الكون · 09-02-2010, 10:07 PM

تستطيع مباشرة أن تضع :

t=0:0.1:30

بدون إدخالها في الحلقة التكرارية

07-02-2010, 11:24 PM	رقم المشاركة : [2 (permalink)]
Abdurauf عضو	r=0.2; %Cooling Constant T=86 ; % Initial Temperature t=0 ; Ts=17; %Surrounding Temperature h=0.1 ; %Step Size nsteps=300 ; for i=0:nsteps fprintf('%0.2f %0.3f\n',t,T) dT=-rh(T(i+1)-Ts) ; T(i+2)=T(i+1)+dT ; t(i+2)=t(i+1)+h; end plot(t,T) t T
Abdurauf عضو

07-02-2010, 11:32 PM	رقم المشاركة : [3 (permalink)]
beho86 عضو	Hello Abdurauf, It worked well, I just made a small change, in the print statement: كود: r=0.2; T=86 ; t=0 ; Ts=17; h=0.1 ; nsteps=3000 ; for i=0:nsteps dT=-rh(T(i+1)-Ts) ; T(i+2)=T(i+1)+dT ; t(i+2)=t(i+1)+h; fprintf('%0.2f %0.3f\n',t(i+1),T(i+1)) end plot(t,T) Now, how the program will differs, when I add the cream at the beginning or at the end of the 5 min?! Beginning, I should subtract 5 from the first cell, and update the rest of the cells. End, subtract 5 from the last cell only. Thanks so much for your help التعديل الأخير تم بواسطة beho86 ; 08-02-2010 الساعة 12:46 AM. سبب آخر: update
beho86 عضو

09-02-2010, 10:07 PM	رقم المشاركة : [4 (permalink)]
أسماء الكون عضو	تستطيع مباشرة أن تضع : t=0:0.1:30 بدون إدخالها في الحلقة التكرارية
أسماء الكون عضو

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