## How to solve a nonlinear PDE system?...

I am currently working on FDM ,i have 2 coupled nonlinear pde ,i need help in solving these equation using maple code.

> restart:

> alias(f=f(tau,eta), theta=theta(tau,eta));

>

> PDE1:=S*diff(f,tau,eta)=eta^2*diff(f,eta)^2+(6*eta^2-2*f*eta)*diff(f,eta)+(6*eta^3-f*eta)*diff(f,eta,eta)-eta^4*diff(f,eta,eta,eta);

> PDE2:=eta^4*diff(theta,eta,eta)+2*eta^3*diff(theta,eta)-Pr*(f*eta^2*diff(theta,eta)+S*diff(theta,tau))=0;

## Why is white space stripped when pasting into this...

The code I write is properly indented.  The operation of pasting it here strips the white space and makes it hard for the reader to comprehend the structure. Manually restoring the appropriate indentation is doable but tedious, made more so because the characters we see here are in a variable width font.  The rationale might be that, given a variable width font the indentation is going to be inconsistent, but that isn't the case if the preformatted style is used, which I do, for code.

Is there any way to turn off the white space stripping?  Presumably this is some ridiculous xml-based processing feature.

## Maple expression input oddity...

sqrt(5) gives

sqrt(1+sqrt(5)) gives "You have entered an invalid Maple expression"

sqrt(u) gives

sqrt(1+u); gives "You have entered an invalid Maple expression"

when using the Maple Math icon. How can I get the correct input for the two expressions?

## Can't save managed tags

MaplePrimes

Most of the tags in this question example are rediculous "the, you, is, and, help, how," etc... .  I tried editing them but I cannot save tags to remove junk tags.  Above all, the most important tag to the question Poincare is not there.  This specific issue is for the recent question  http://mapleprimes.com/questions/207460-Poincare-Section

## Fighting spam

by: MaplePrimes

As some of you have previously mentioned, we have seen an increase in the amount of spam on MaplePrimes over the past few months. We recently took steps to improve it in a recent update that has so far proven helpful, and have also increased our behind-the-scenes efforts to proactively remove and block spam accounts.

Today we made a couple of additional minor changes to member profiles that should help further. Specifically, members can no longer enter HTML tags in the biography, 'technical interests/fields', and 'other interests' sections within their profiles. Spammers were co-opting these areas to create links back to their sites, and it is our hope that MaplePrimes will become much less attractive to them now that the capability has been removed.

In addition, we de-activated a large number of accounts (with 0 reputation) that were using these fields for spam. Prior to taking this action, we reviewed the records we were deactivating, and did not see any evidence of legitimate members. However, there is a small chance that we blocked a legitimate account in the process of doing this. If this has occurred to you, please accept my apologies and send an e-mail to custservice@maplesoft.com and we will reactivate it quickly.

## The high cost of improving a forum

MaplePrimes

I hope that in the future if mapleprimes ever does another overhaul that it does NOT do what has recently been done at the mathematica forum I just came across. http://community.wolfram.com/groups/-/m/t/744097?p_p_auth=AfGyGp7X

Mapleprimes has endured a forum change from primes1 to primes2(current forum) and all posts/questions have for the most part remained intact, and have been repaired or fixed by the developers if pointed out .. thumbs up for Maplesoft and Mapleprimes developers for retaining all forum data.  Most posts that didn't have a home were simply relocated, but are still accessible.

In the case for mathematica, a whole student forum was removed and is being scrutinized, and decided by mathematica developers whether or not the post should be put back into the forum (currently none of the posts have been restored).  I would think that would be most dissappointing from any user standpoint.

## Mapleprimes improvements - add Workarounds categor...

MaplePrimes

Off to the right of mapleprimes we have Recent Questions/Maplesoft Blog Posts/Recent Posts and Active Conversations.

I propose to have the category Workarounds added.

There are two instances I can think of that would be beneficial for Maple users that would belong here.  The most recent one http://www.mapleprimes.com/posts/201844-Possible-Bug-In-Maple- and one regarding issues adding the dissipative term to the heat equations http://www.mapleprimes.com/questions/97391-Whats-Wrong-With-Maple-Solution

Users of older versions of Maple or even current Maple versions not yet updated would find this quite useful.

MaplePrimes

There are some great comments and replies by users that are worth upvoting.   Also choosing as best answer to some posts that were converted from questions would also be helpful here at mapleprimes.

## Some legitimate users erased...

There are no users with 0 reputation.  It appears all users with 0 reputation and negative reputation have been erased.  One user I can not find who is or now was a legitimate user is John Mcloone an employee at Mathematica who made a post here.  I can only think during the recent spam attack that all users with 0 or negative reputation were removed.  Some of those users had legitimate questions.  Where did those users, John Mcloone and their posts go?

## gdb crashes when linking to OpenMaple library...

I use Maple18 on unix 64. I have the MAPLE and the LD_LIBRARY_PATH properly set up to use OpenMaple. When I link my code to OpenMaple library I get segmentation fault when I try to debug using gdb. In order to isolate the problem, I created a simple temp.cc file that contains the following:

#include <string>

#include <stdio.h>

int main()

{

int x = 10;

std::string abc;

abc = "testString";

printf("this is it %s\n", abc.c_str());

}

When I compile the code using g++ -g -o temp temp.cc I can run ./temp and step into the code using gdb with no problems.

If I link to Maple Library g++ -g -o temp temp.cc -L/opt/maple18/bin.X86_64_LINUX –lmaplec

I can run the code ./temp but I can not step into it using gdb. I get the error as shown below when I try to step over std::string abc.

//-----------------------------------------------------

GNU gdb (GDB) 7.8

Copyright (C) 2014 Free Software Foundation, Inc.

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law.  Type "show copying"

and "show warranty" for details.

This GDB was configured as "x86_64-unknown-linux-gnu".

Type "show configuration" for configuration details.

For bug reporting instructions, please see:

<http://www.gnu.org/software/gdb/bugs/>.

Find the GDB manual and other documentation resources online at:

<http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".

Type "apropos word" to search for commands related to "word"...

(gdb) b main

Breakpoint 1 at 0x40091f: file temp.cc, line 6.

(gdb) r

Starting program: xxxxxxxxxxxxxxxxxxxxxxxxxxx

Breakpoint 1, main () at temp.cc:6

6         int x = 10;

(gdb) n

7       std::string abc;

(gdb) n

BFD: reopening /tmp/xf-dll/xf-1274259bc6684076beea8652f625b03bf2133.tmp: No such file or directory

BFD: reopening /tmp/xf-dll/xf-1274259bc6684076beea8652f625b03bf2133.tmp: No such file or directory

BFD: reopening /tmp/xf-dll/xf-1274259bc6684076beea8652f625b03bf2133.tmp: No such file or directory

Can't read data for section '.eh_frame' in file '/tmp/xf-dll/xf-1274259bc6684076beea8652f625b03bf2133.tmp'

0x00000000004007a8 in std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string()@plt

()

(gdb) n

Single stepping until exit from function _ZNSsC1Ev@plt,

which has no line number information.

Segmentation fault

## Option to sort Mapleprimes by date of original...

MaplePrimes

Mapleprimes should have an option to sort Mapleprimes by the date of the original poster.

## How to remove block ?...

There have come unwanted lines and marks . I donot know how to remove them. Using doc.block, remove block seems to be little tough to incorporate! Please enlighten me. Modified doc. is most welcome. Thanks. Ramakrishnan V

 Gaussian Elimination Method

 (1)
Coefficient Tanle
 Equation 1 Equation 2 Equation 3 Equations =  =  =

The equations in matrix form is given by

 (2)

The Gaussian Elimination gives the simplified natrix equation as given below:

 (3)

The equations in simplified form are:

 (4)
 (5)
 (6)

The aolution ia obtained by solving the above equations in reverse order

 (7)

## Why are old posts becoming active?...

Why have there been so many old Posts and Questions moving to the top of the Active Conversations stack the past two days, even though they have no new activity? This makes MaplePrimes very difficult to use! Please make it so that the Active Conversations stack is sorted by the actual time of the most-recent addition to the thread.

## MaplePrimes Update - New Tools for Spam, Saving...

by: MaplePrimes

Earlier today, we published some changes to MaplePrimes in order to add some new features that have been requested by our users.

Delete as Spam

Users with a reputation score above 500 have always had the ability to remove inappropriate or spam posts using the Delete function. As of this update, a Delete as Spam feature has been added that provides some additional capabilities targeted directly at the spam messages that are posted on MaplePrimes. When this feature is used, the following occurs:

• The message is deleted
• The author's account is marked as a spam account and blocked
• All other messages from the author are removed

Since this is a powerful feature, there are also some safeguards in place to prevent accidents from occurring:

• Only users with a reputation less than 10 can be removed in this way
• In the event that content is ever inadvertently removed, MaplePrimes administrators have the ability to restore content removed in this way.

Hopefully, these features make it much more difficult for spam accounts to get traction on MaplePrimes, and also reduce the time involved in policing the spam that is posted.

Draft Messages

You now have the ability to save a message as a draft so that you can come back to it later. All draft messages are saved in your profile and can be managed by clicking the account option at the top of every page.

Some powerful searching capabilities have been added to MaplePrimes with the addition of a new Advanced Search feature. Using this search allows you to quickly find questions or posts within a particular date range, by author and/or by tag.

Save page as PDF

We know that some of our members maintain personal archives of MaplePrimes content, and to make this easier, we have added a feature that generates a PDF copy of a page. This option is available in the More area that appears under every post and question.

Your MaplePrimes user profile page has always included archives of your posts, questions and answers. With today's update, replies are also available.

In addition to these, some other minor changes & fixes were made.

As always, thank you very much for your dedication to MaplePrimes and for your suggestions. We hope that you find these features useful and look forward to other ideas that you have!

## They're watching...

by: MaplePrimes

Like most companies today, Maplesoft monitors its website traffic, including the traffic coming to MaplePrimes. This allows us to view statistical data such as how many total visits MaplePrimes gets, how many unique visitors it gets, what countries these visitors come from, how many questions are asked and answered, how many people read but never respond to posts, etc.

Recently one of our regular MaplePrimes users made the comment that MaplePrimes does not reach new Maple users. We found this comment interesting because our data and traffic numbers show a different trend. MaplePrimes gets unique visitors in the hundreds of thousands each year, and since its inception, it has welcomed unique visitors in the many millions. Based on these unique visitor numbers and the thousands of common searches specifically about Maple that people are doing, we can see that many of these unique visitors are in fact new Maple users looking for resources and support as they begin using Maple. Other visitors to MaplePrimes include people who use Google (or other search engines) to find an answer to a particular mathematics or engineering question, regardless of what mathematics software they choose to use, and Google points them to MaplePrimes. There are some popular posts that were written months, even years ago, that are still getting high visitor views today, showing the longevity of the information on MaplePrimes.

MaplePrimes gets the majority of its visible activity from a small number of extremely active members. In public user forums around the world, these types of members are given many names – power users, friendlies, evangelists. Every active public user forum has them. On MaplePrimes, it’s this small number of active members that are highly visible. But, what our traffic data reveals is the silent majority. These people, many of them repeat visitors, are quietly reviewing the questions and answers that our evangelists are posting. The silent majority of MaplePrimes visitors are the readers; they are the quiet consumers of information. For every person that writes, comments on, or likes a post, there are thousands more that read it.

Here are a few more MaplePrimes traffic data points for your reference:

• MaplePrimes is very international and draws people from all around the world. Here are the top 10 countries where the most MaplePrimes visitors come from:
1. USA
2. India
4. Germany
5. China
6. United Kingdom
7. Brazil
8. Australia
9. France
10. Denmark
• Here are the top 5 keywords people are using in their searches on MaplePrimes:
1. Data from plot
2. Physics
3. Sprintf
4. Size of plot
5. Fractal
• MaplePrimes is growing at a very fast rate: Traffic (visitors to the site) and membership size is growing at nearly double the pace it was last year. The total number of posts and questions this year is also much higher compared to the same timeframe last year.
• Our top 5 MaplePrimes members have each visited MaplePrimes more than 1200 times and viewed a combined total of more than 10,000 pages (that is total page views, not unique page views). Our top 25 MaplePrimes members have visited at least 250 times each (many of them nearly 1000 times each) and our top 50 MaplePrimes members have visited a combined total of over 23,000 times, visiting nearly 200,000 pages. Thank you! We’re glad you like it. :-)

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