Whoa !!  No wonder no one posted an answer here.  It is a bit confusing. 

Anyone wishing to look further into this question (I decided to search and find and found)  can follow his work in length here
http://www.cheresources.com/invision/topic/14619-shell-and-tube-condenser-design/

There had been some considerable questioning and answering before he came here to mapleprimes and maple for some help.  It is, though, an interesting read.

I was actually fooled into thinking Samir Khan had come back to visit mapleprimes with a post (a celebration ensues over some interesting possible engineering marvels with maple that will come with his return) however, the celebration was extremely short lived when I saw it was unfotunately a post from the past. 

Just trying to figure out how one would type what YC has shown without the `*` in the entry line and getting it to show up in the answer.

Was able to type it out what he shows in his worksheet on Maple16 classic, document and worksheet mode and I was unable to replicate what YC has shown (all gave the answer of 1) except using his worksheet. 

He must have copy and pasted it from somewhere and Maple hid the `*` from view.  Curious as to the reasons why.

Just trying to figure out how one would type what YC has shown without the `*` in the entry line and getting it to show up in the answer.

Was able to type it out what he shows in his worksheet on Maple16 classic, document and worksheet mode and I was unable to replicate what YC has shown (all gave the answer of 1) except using his worksheet. 

He must have copy and pasted it from somewhere and Maple hid the `*` from view.  Curious as to the reasons why.

What do I get when I buy Maple 16?  Do I get hardcopy manuals?  Does a Maple 16 personal edition still exist?

@ Alejandro Jakubi - The above intended usage for dual worksheets is for comparison purposes.  Opening a new kernel and trying to open the already opened worksheet redirects me to the already opened worksheet.  I suppose I'll just save the same worksheet with two different names.

I still hear that Maple is not strong in numerics - however I find it very much adequate although others will probably disagree, and for that reason I pose a Maple 17 wish ... stronger numerics for Maple ... 

One can not measure the quality of a website accurately depending on the definition of quality being used.  The values obtained are objectionable especially if they are based on activity.  The word quality is also objectionable - quality as in content / layout or quality as in good connection, speed of information delivery etc...

I restarted and achieved the same result but if I do some other operation in the midst or just after restart the value changes slightly. 

For example, I first changed epsilon and sigma to rational values  epsilon:=convert(epsilon,rational) etc.. and of course I should observe a slight change  685.116351816730684 as you can see more decimal places have changed value. 

I also get different values if I simply restart; by itself or restart; gc():  different again if I went restart; with(plots):

Not really sure why adding with(plots) would affect the value.

Maple 12 and 15 and most likely all the versions in between and prior to 12 that work with the code give one numerical answer. 

Seeing Maple 16 showing a different value could mean 3 things ...

   1 - All Maple versions prior to 16 were carrying some kind of numerical bug.

   2 - Maple 16 has some kind of numerical bug
or
   3 - Since the pdsolve command for Maple 16 is slightly changed, there were probably a few more calculations and loops involved carrying numerical values through causing a slight value change.

I suppose if we increased the number of digits involved we would improve the accuracy and get better correlation between the numbers.  Maybe someone with M16 could verify that it is indeed what is occurring?

@pagan So you think that's okay?

I still say mapleprimes 1 had the best layout. 

The layout and functionality of mathoverflow is terrible.  I would be more upset if Mathematica echoed the old mapleprimes 1 as they would have much success with it.  Having mapleprimes 2 try to emulate after some other website wasn't the best idea. 

One would want to use as simple as possible secondary pde

using pde:=diff(u(x,t),t)=u(x,t)^2 works fine however setting it to a constant or u(x,t) the solution works as the old way with the wrong answer. 

One would want to use as simple as possible secondary pde

using pde:=diff(u(x,t),t)=u(x,t)^2 works fine however setting it to a constant or u(x,t) the solution works as the old way with the wrong answer. 

Thanks Preben.  It works great!  I do not know what I was doing wrong, I'll find my error later, thanks again.

**edit ** I found that my error was a typo on the secondary pde.  The choice of your secondary pde however independent of the original should also be valid.

Thanks Preben.  It works great!  I do not know what I was doing wrong, I'll find my error later, thanks again.

**edit ** I found that my error was a typo on the secondary pde.  The choice of your secondary pde however independent of the original should also be valid.