Cobweb graph
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I want to draw a cobweb graph for sin(x). Here is a code (based on an online source) that seem to fail to work, grateful if someone could help me troubleshoot or suggest a better code.
function cobweb(f,a,b,x0,x1,N)
x(1)=-2; % plot orbit starting at x0
for i=1:99
x(i+1)= sin(x(i));
plot([x(i),x(i)],[x(i),x(i+1)]);
hold on
plot([x(i),x(i+1)],[x(i+1),x(i+1)]);
hold on
end
hold off
Thanks.
2 个评论
Fangjun Jiang
2011-8-20
What is failing? Don't assume everybody knows cobweb graph. This is a MATLAB forum.
Richard
2011-8-21
采纳的回答
Paulo Silva
2011-8-21
0 个投票
9 个评论
Fangjun Jiang
2011-8-21
Don't! If it's a homework, that's too much help!
Oleg Komarov
2011-8-21
Too late! The OP was smart enough to get a link :)
Fangjun Jiang
2011-8-21
@Oleg, ??
Paulo Silva
2011-8-21
The OP said "...or suggest a better code.", I just did the suggestion, anyone can find examples of code online, now if it's really homework and the OP delivers it without understanding the code and gets a bad grade it's not our fault, it's really his fault for being lazy. If on the other hand the OP takes time to understand the code and adds comments or changes/improves it, that would be great.
Richard
2011-8-21
Oleg Komarov
2011-8-21
@Fangjun: the OP posted a very concise request in a polite way, he's given a properly formatted sample snippet which appears to be the core of the cobweb plot (from Paulo's link). It has shown enough to tell him apart from people that claim spending a week on problems as what 1:10 means so he deserved the link that Paulo suggested.
Also as Paulo correctly points out, understanding the code in the link (as opposed to simply using it) would be more than enough for a hypothetical homework.
@Richard: if you feel that the link suggested by Paulo is what you were looking for, please accept his answer.
Richard
2011-8-21
Fangjun Jiang
2011-8-21
@Oleg, The question may be concise. But it's not a good question at all according to your "TUTORIAL: how to ask a question ..." post.
First, there is no explanation or reference to "Cobweb graph". Second, the vague "fail to work" claim. Third, even the further comment "It just doesn't plot" is not accurate. It plots but maybe not as expected.
Now take a look at the OP's original code. There are many input arguments but none was used. So I would assume the code was work-in-progress. Paulo's link provides a complete code with almost identical arguments. That's why I said the help was too much. We are all here to help with MATLAB questions. But I didn't see a MATLAB question.
Everybody can do a search and find some links. If the OP found Paulo's link, that's great. He did a good research. But apparently he didn't.
Oleg Komarov
2011-8-21
@Fangjun: I said at first he was "smart enough" and then he was able "to tell him apart from": I wasn't trying to say, as it may have appeared from the first sentence of my previous comment, that his question was in absolute terms very good.
I am not here to uncover people as free-riders at all costs (or to classify as such). I just didn't feel "fooled" as it may happen with some other posts and that's why I would have posted a comment or maybe (who knows) a link, which on the other side can't be considered in absolute terms a complete answer.
更多回答（1 个）
Fangjun Jiang
2011-8-20
0 个投票
There is a nice animation here. I think it needs some if-statement in your code.
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