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Feel free to correct the grammar mistakes in my posts.


Feb
5
comment Green's Function in Mathematica
v5.2……well it's really too old, a lot of improvement has been made in the following version……you'd better upgrade your Mathematica.
Feb
5
comment Mathematica can't find constants for this differential equation
Well, I doubt if Assuming and $Assumptions will help in this case for they only work for functions with the option Assumption. DSolve doesn't have this option, and there seems to be no evidence that DSolve has called functions with this option…
Feb
5
comment Green's Function in Mathematica
Er… Just to confirm, DSolve won't work without Assuming in this case? Are you in v9? In v8.0.4, the Assuming isn't needed.
Feb
5
comment Green's Function in Mathematica
Your first code sample doesn't work? It is solvable in v8.0.4.
Feb
5
comment Kinetic Friction in Mathematica, weird behaviour
I found it, see the 3rd approach in my answer.
Feb
5
revised Kinetic Friction in Mathematica, weird behaviour
add the 3rd solution.
Feb
4
comment refer to result of cell above current cell?
Yeah, the number depends on the evaluation order. If you need to use the output of a specified cell for times, it's better to give a name to it.
Feb
4
comment refer to result of cell above current cell?
You can use the index of the output to refer to it. For example, if it's Out[32] you can refer to it by %32.
Feb
4
comment Kinetic Friction in Mathematica, weird behaviour
In v8.0.4, MaxStepSize -> .01 doesn't work, but MaxStepSize -> .03 does. I think that a more strict control for the step is needed, though I don't know how to achieve that…
Feb
4
revised Kinetic Friction in Mathematica, weird behaviour
added 893 characters in body
Feb
4
revised Kinetic Friction in Mathematica, weird behaviour
added 88 characters in body
Feb
4
answered Kinetic Friction in Mathematica, weird behaviour
Feb
4
comment Error in using EventLocator in NDSolve
Without a complete code sample, it'll be hard for others to figure out the reason… If the original definitions of V and G are really long, you can provide a simplified version reproducing your problem. BTW, if you add @xzczd at the beginning of the comment, I'll get a remind.
Feb
2
accepted Why I need Evaluate for the Plot of the probability density function of PolyaAeppliDistribution?
Feb
1
revised How to choose MaxStepFraction for optimal speed of NDSolve
Retag
Feb
1
comment How to choose MaxStepFraction for optimal speed of NDSolve
I just come to mention that all of your MaxStepFraction don't "converge" for L = 5 in v8.0.4. (Vista Home Basic 32bit. BTW, 2GB memory so it can't bear the L = 7.5 case 囧.) And according to my experience, warning messages of NDSolve isn't a big deal for many cases. With the method mentioned in this post your warning will disappear but in fact the result doesn't change much.
Jan
29
comment How to use Compile with NDSolve function for large no of differential equations?
I remembered once I read some material (probably in somewhere inside the document) that said NDSolve will use Compile automatically…
Jan
26
comment Extract the generating curves from a Graphics3d returned from RevolutionPlot3D
@belisarius You got it! It's called "母函数" in Chinese. (There exists a more straight translation "生成函数" though.)
Jan
26
comment Extract the generating curves from a Graphics3d returned from RevolutionPlot3D
@Mr.Wizard Well, I didn't expect it's so hard to find a detailed explanation for this word……Dictionaries (for example, this: thefreedictionary.com/generatrix) do include it though. This word can be found in the wiki page of cone.
Jan
26
comment Extract the generating curves from a Graphics3d returned from RevolutionPlot3D
@Mr.Wizard A equivalent of "generatrix", I believe. "Generatrix" is called 母(mother)线(line) in Chinese.