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Topics - Victor Ivrii

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436
Misc Math / Bonus Web Problem 1
« on: October 09, 2012, 03:49:08 PM »
This is not very difficult problem but it contains one tricky point

Consider heat equation with thermo-conductivity depending on the temperature:
\begin{equation}
u_t= (u^m u_x)_x
\label{eq-1}
\end{equation}
with $m>0$ and find solution(s) $u$ which are self-similar
\begin{equation}
u_\lambda:= \lambda u(\lambda x, \lambda^\gamma t )=u(x,t)\qquad \forall \lambda>0
\label{eq-2}
\end{equation}
and
\begin{equation}
u(x,t)\to 0 \qquad\text{as  } x\to \pm \infty.
\label{eq-3}
\end{equation}
Hint: first find $\gamma$ and then plugging $\lambda =t^{1/\gamma}$ reduce $u$ to a function of one variable and PDE (\ref{eq-1}) to ODE (Follow lecture 9 with the necessary modifications)

437
APM346 Announcements / Week Oct 8--12 TA office hours
« on: October 09, 2012, 03:15:36 PM »
When: Wed Oct 10 from 5 to 6 pm
Where: Lounge area on the sixth floor of the Bahen building

Martin will hand back Homework Assignment 1 and answer any questions.

438
General Discussion / The purpose of this forum
« on: October 08, 2012, 01:49:07 AM »
The main purpose of this forum is not the communication with instructors but peer-to-peer. I noticed that some of you answer the questions of your peers and I really appreciate, but I would like to see more -- much more -- of this!

439
APM346 Announcements / Week October 8--12: office hours of Victor Ivrii
« on: October 04, 2012, 04:30:08 AM »
Next Monday (October 8, 2012) will be no office hours (Thanksgiving)

Instead there will be Office Hours

  • Tuesday (October 9) 3:00--5:00 (HU1008)
  • Wednesday (October 10), 1:30--3:30 (HU1008) -- the last chance to submit HA3

All office hours in HU 1008

440
General Discussion / Registration has been tightened
« on: October 03, 2012, 01:52:18 PM »
Due to spammers--actually wannabe spammers--the were erased by admins before causing any harm--registration has been tightened: ReCaptcha has been upgraded, security questions changed and registration from Immediate became Requires email validation (next step--Requires approval by admins).


442
APM346 Announcements / Term Tests
« on: September 26, 2012, 03:02:02 PM »
Both sections:

Term Test 1
16-OCT-12 EX 200 16:00--18:00 (TUE) Examination Facility http://osm.utoronto.ca/osm/exam_200.html

There is a poll attached. Answer it please and select the topmost answer which works for you. If nothing works contact class coordinator Prof. Colliander

Term Test 2  15-NOV-12 (THU) 18:00--20:00
GB 304 Galbraith Building  http://osm.utoronto.ca/class_spec/f?p=210:1:1579690136306710::NO::P1_ROOM:304
GB 404  Galbraith Building http://osm.utoronto.ca/class_spec/f?p=210:1:1579690136306710::NO::P1_ROOM:404
GB 412 Galbraith Building http://osm.utoronto.ca/class_spec/f?p=210:1:1579690136306710::NO::P1_ROOM:412

443
APM346 Announcements / Please register ASAP
« on: September 25, 2012, 02:15:10 AM »
So far registration is easy: instant one without approval by admin. However it will not last forever. Monday night in the break of the class was observed the first wannabe spammer (from Poland) and the account was publicly deleted :D

This means that bad guys will come in the force soon and then registration will be changed--only with admin approval. So, harry up before it happens!

444
Home Assignment 1 / WTH?
« on: September 25, 2012, 02:08:17 AM »
Aida, WTH? In MAT244 your scan was a golden standard of scanning
http://weyl.math.toronto.edu:8888/MAT244-2012S-Forum/index.php?topic=38.msg111#msg111 (see, I remember, so good it was), and now this? Such posts defy the whole purpose of this forum, it is not to submit your papers for grading (you submit it to TA) but even this is difficult as quality of scan is poor (actually you used cellphone without taking care of settings), but to share the solution with your classmates who can comment, find errors or correct them.

From this point the typed solution using MathJax is far the best as I can edit it, just marking the place where I see an error, and anyone can copy-paste code from it. But apart of this your former clean black-white scan with perfect position of the paper was the very best thing.

Here you use colour (not even grayscale) scan and some papers are horizontal and some diagonal ... everyone has a really hard time to read them. I admit, some of your submissions a better than othersbut  from the point of view of this forum I must consider all of them non-existent :(. It looks like you just decided to capture the space preventing anyone else from posting the solutions.

So, everyone should feel to post solutions.

------

Also:
some people used paper clips despite our request to staple and some even tried to use "poor man paper clips" just folding several times the corner of the paper and adding a bit of saliva. Sorry, no of these constructions is robust enough to prevent separation of pages. I hope I caught every such attempt and stapled, but I am not sure. I am also not sure if Prof Colliander managed with this. So, if you have not stapled and your pages are separated and lost, you know whom to blame.

Not everyone indicated the section where to bring your papers back (so get such papers from TA who graded it).

Please use the standard paper (letter size). Someone used A4 (a bit more narrow and a longer overseas size). It looks like a little thing but also causes problems when dealing with tens of papers.

And finally, again: please, do not come to submit papers during the class -- only before lecture, during the break or after. Everyone in the night class feels tired (instructor in the least degree because of adrenalin rush) and such distractions are rather disruptive.

445
Home Assignment 1 / HA1-pdf
« on: September 22, 2012, 01:40:44 PM »
Here is HA1.pdf - Home assignment 1 printed to pdf (updated Mon 24 Sep 2012 05:03:22 EDT)

448
Technical Questions / Testing Math
« on: September 18, 2012, 11:59:02 PM »
Testing how MathJax was hooked up
\begin{align*}
u(x,t)= &\underbracket{\frac{1}{2}\bigl[ g(x+ct)+g(x-ct)\bigr]+\frac{1}{2c}\int_{x-ct}^{x+ct} h(y)\,dy}_{=u_2}+\\[3pt]
 &\underbracket{\frac{1}{2c}
\iint_{\Delta (x,t)} f(x',t' )\,dx\,d t' }_{=u_1}.
\label{eq-4}
\end{align*}

449
APM346 Announcements / Welcome to APM346 Forum
« on: September 18, 2012, 06:40:19 PM »
Welcome to this course forum.

It runs in conjunction with this course website. More permanent and systematic information is placed on website, while forum is for discussion.

In particular, it would be nice to register as "John Smith" or "johnsmith" rather than "PDE Monster" or ....
However  you can always change your screen name   (the one which everybody sees):  Open Profile > Account Settings and look for "Name" (and a screen name as "John Smith" would be preferable).

 BTW you can have a cool avatar too. Please do not display any confidential info.

You cannot change the loginname (used for login).  But there is no need.  Nobody except you knows your password - even Admins - but Admins don't need  to know it.

Some forum rules
  • Please use different boards according to their description (I will create new ones if needed)
  • Do not hijack topics: if the topic is devoted to some question, do not post anything which is not related. Start a new topic. 
  • On the other hand, do not start new topic answering to the existing post; use the same topic.
  • Do not put in the same post several not related things - make several posts instead (in different topics).
  • Post solutions to Home Assignments not earlier than 1 day after deadline to submit (normally Tuesday night) 30 min after deadline to submit  (normally Monday 21:30);
  • Do not post solution which coincides with the solution already posted by someone else;
  • Use common sense.

Have questions?
If you have a question which you think is of general interest—ask it here rather than via email.

MathJax
This forum (and website) use MathJax to display mathematics. However hooking MathJax broke preview in many browsers (but not in Safari, Chrome or other WebKit based browsers). Still, you can always modify your post.

Blackboard
Blackboard https://portal.utoronto.ca/, Partial Diffl Equat/Partial Diffl Equat Fall-2012-APM346H1-F-LEC5101.LEC0101, will be used only for marks, occasionally for copies of  the important announcements and emails.

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