Wolfram Mathematica

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b3m2a1

02:18

I packaged up my stylesheet editing code. Makes life a lot better when working with stylesheets. But now the question is what answers should I use to let people know it exists?

4 hours later…

BAYMAX

06:35

@ChrisK Thank you for looking

Can I invite you to Dynamical Systems and Chaos theory Chat room to discuss about this further?, it would be very helpful!.

1 hour later…

b3m2a1

07:37

This is hilarious: BoxForm`GenericIcon[Region`SemialgebraicRegion]

eMM

07:53

@b3m2a1 Hello!

b3m2a1

@eMM Hi what's up?

eMM

do you have some time to explain me infix, prefix and postfix please..

b3m2a1

Sure thing

eMM

thanks =)

b3m2a1

We'll start by considering the most basic case of setting up an expression (or really a Construct call) head[args]

eMM

07:56

ok..

b3m2a1

Infix, Prefix, and Postfix just do that

Infix does it with head in-between two arguments:

arg1~head~arg2

Prefix does it with head before a single argument: head@arg1

Postfix does it with head after a single argument: arg1//head

But they all are just ways to represent head[args]

eMM

ok.. makes sense to me..

arg1~head~arg2:
1+1
so the prefix equivalent is:

+1+1

b3m2a1

Yeah basically. Another way to think of it is Infix is for a binary operator while Postfix and Prefix are for unary operators.

eMM

((1+2)*5)-3
How to convert this Infix expression to its Prefix and Postfix equivalents respectively without the help of a programming language?

b3m2a1

08:11

All of the operators are binary so Prefix and Postfix don't apply here

eMM

I see..

eMM

08:31

@b3m2a1 thanks so much.. gotta go now, bye!

b3m2a1

Glad to help

2 hours later…

Sjoerd C. de Vries

10:32

@b3m2a1 Good call! Indeed, if you look at the below I can understand the reason for the message.

inv() must necessarily make a copy as it changes the input, whereas transpose() still refers to the input, but has a different 'view' on it. This is a bit nasty as Python is still able to output both values, but Mathematica can't. I'm still tempted to say that's a bug.

This is in IPython:

4 hours later…

Chris K

14:26

@BAYMAX I might not be the best person to ask - maybe just formulate a question for the site here? But try to include a simple, yet concrete example (not just abstract matrices, give the full system)

BAYMAX

15:21

@ChrisK please help me formulate the question, I am trying to solve this since many days, I also asked in main but unfortunately, I did not get any response, perhaps you are the first to respond...actually I have asked this question Query on Master Stability Function applied in case of Diffusively coupled Chua circuits.

and then after that Computation of largest Lyapunov exponent from the Variational equation.

Actually I could not find anywhere expressions other than abstract matrices

Perhaps they are doing for a general case

Also if you see this article equations 2,3,4,6,7 all have the variational equations

ALso there is an example in pg-6 sec -4

Meta

16:13

Q: Looks like the Wolfram Programming Cloud doesn't work anymore for me

Today, I signed into my account at Wolfram Programming Cloud. I opened a new notebook and typed some commands but didn't get any results no matter how much I waited. Even ironically, a command as simple as 2+2 didn't produce any output, and even more ironically, the commands I type get disappeare...

discussion

Chris K

16:43

@BAYMAX This sounds very intersting and I'd love to be able to help you out, but this is pretty technical and outside my expertise. Do you know how to calculate Lyapunov exponents for a simple, uncoupled system? If not, I'd start there.

My guess is when they say "J is the usual Jacobian of any node" they implicitly assume that it is a time-dependent function of the nonlinear system -- see eqns 24-25 where they do denote this dependence. Anyhow, I hope you get help with your problem, because it seems like an interesting topic.

BAYMAX

@ChrisK Hi, thank you very much for your willingness to help me!, I am sorry but actually I never calculated/ computed Lyapunov exponents for a simple, uncoupled System, can you please help me?

I just need a bit of guidance and I hope I can manage from there on

It would be helpful to see how we can relate the Lyapunov exponents of uncoupled system with the coupled systems?

Chris K

Sorry I don't have time to help you. Here are some notes I found recently that give a nice explanation: cs.colorado.edu/~lizb/chaos/variational-notes.pdf

BAYMAX

16:59

Thank you for your time, I will read this and will be in touch with you after reading this!

@ChrisK