stability

ahmedtuwien · July 6, 2017, 09:01

i just need awith these 2 question
b and c in attachement

lcarasik · July 6, 2017, 11:07

Quote:

Originally Posted by ahmedtuwien

i just need awith these 2 question
b and c in attachement

What have you attempted so far? What specifically are you having trouble with? This isn't a "we do your homework for you" forum.

ahmedtuwien · July 6, 2017, 11:13

i solved b and c but i cant start with d i dont understand it

ahmedtuwien · July 6, 2017, 11:16

and i have to say when u help me to start solving doesnt mean that i need you to do homework for me .please take care of waht u say

lcarasik · July 6, 2017, 11:18

Quote:

Originally Posted by ahmedtuwien

and i have to say when u help me to start solving doesnt mean that i need you to do homework for me .please take care of waht u say

By just stating, "I need help or I don't know" doesn't give any information for the readers to understand what you are having trouble with.

arjun · July 6, 2017, 11:32

Quote:

Originally Posted by ahmedtuwien

and i have to say when u help me to start solving doesnt mean that i need you to do homework for me .please take care of waht u say

What you are asking could be figured out from simple google search. Even the wiki entry about temporal scheme shall mention it. Milovan Peric's book has a whole chapter discussing this.

What you asked is indeed your homework. You shall understand that a great number of people here are quite busy people and your problems are important to you, not to them. Someone would not want to spend time with something that is just two google searches away.

ahmedtuwien · July 6, 2017, 11:38

oki sorry thats my solution

ahmedtuwien · July 6, 2017, 11:40

Hier are my solutions for b and c if you have any idea how i solve d will be nice

ahmedtuwien · July 6, 2017, 11:42

sorry but what i know is that forum is a place to discuss the ideas and help others for those who have time to discuss and help

FMDenaro · July 6, 2017, 13:30

Guide: How to ask a question on the forums

LuckyTran · July 6, 2017, 17:46

I reflect others opinions that this Forum isn't for homework. With that said....

Just follow the instructions. In (d) you are to discretize (4) and arrive at something looking similar to (3) or (5). Compare the new equation you have with (3) and hence show that the new discretized equations are no longer (3), which is a centered scheme, but is equivalent to using an off-centered scheme. Presumably you already have deduced the discretized equations for an off-centered scheme in an earlier problem. If not, then you need to derive it.

For (b) and (c), I have not looked at your notes nor do I understand the intent of the text. But one way to analyze stability is to what is asked in (e), write down the equations and consider the conditions for b to be positive-semidefinite. If b might be negative, you can get oscillatory solutions.

ahmedtuwien · July 6, 2017, 17:56

Quote:

Originally Posted by LuckyTran

I reflect others opinions that this Forum isn't for homework. With that said....

Just follow the instructions. In (d) you are to discretize (4) and arrive at something looking similar to (3) or (5). Compare the new equation you have with (3) and hence show that the new discretized equations are no longer (3), which is a centered scheme, but is equivalent to using an off-centered scheme. Presumably you already have deduced the discretized equations for an off-centered scheme in an earlier problem. If not, then you need to derive it.

For (b) and (c), I have not looked at your notes nor do I understand the intent of the text. But one way to analyze stability is to what is asked in (e), write down the equations and consider the conditions for b to be positive-semidefinite. If b might be negative, you can get oscillatory solutions.

Thank you very very much

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July 6, 2017, 11:13		#3
ahmedtuwien New Member Ahmed saad Join Date: Jul 2017 Posts: 7 Rep Power: 8	i solved b and c but i cant start with d i dont understand it

July 6, 2017, 11:16		#4
ahmedtuwien New Member Ahmed saad Join Date: Jul 2017 Posts: 7 Rep Power: 8	and i have to say when u help me to start solving doesnt mean that i need you to do homework for me .please take care of waht u say

July 6, 2017, 11:38		#7
ahmedtuwien New Member Ahmed saad Join Date: Jul 2017 Posts: 7 Rep Power: 8	oki sorry thats my solution

July 6, 2017, 11:42		#9
ahmedtuwien New Member Ahmed saad Join Date: Jul 2017 Posts: 7 Rep Power: 8	sorry but what i know is that forum is a place to discuss the ideas and help others for those who have time to discuss and help

July 6, 2017, 13:30		#10
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,773 Rep Power: 71	Guide: How to ask a question on the forums

July 6, 2017, 17:46		#11
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	I reflect others opinions that this Forum isn't for homework. With that said.... Just follow the instructions. In (d) you are to discretize (4) and arrive at something looking similar to (3) or (5). Compare the new equation you have with (3) and hence show that the new discretized equations are no longer (3), which is a centered scheme, but is equivalent to using an off-centered scheme. Presumably you already have deduced the discretized equations for an off-centered scheme in an earlier problem. If not, then you need to derive it. For (b) and (c), I have not looked at your notes nor do I understand the intent of the text. But one way to analyze stability is to what is asked in (e), write down the equations and consider the conditions for b to be positive-semidefinite. If b might be negative, you can get oscillatory solutions.