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visits member for 2 years, 10 months
seen Dec 16 at 0:43

Sep
23
comment A problem about fixed point iteration theory
I didn't intend to say you are wrong. However, one who does not read carefully might think precision always decreases as computation continues. I wanted to make it clear that isn't always the case.
Sep
21
comment A problem about fixed point iteration theory
From the explanation above you might conclude that the result of a computation always has less precision than the precision than the numbers used in the computation. However, you increase precision in the next two examples. ------- In[1]:= x=SetPrecision[6.2,4.0]; Precision[Erf[x]] Out[2]= 19.9801 In[3]:= Precision[2+(x-62/10-10^-30)^6] Out[3]=19.5467
Sep
19
comment Ted's explanation for the 3rd argument of ListCorrelate doesn't apply to the {1, -1} case?
It looks like I did understand what ListCorrelate does with the third argument, but in that example above, I didn't use the right way of rotating the kernel. I wrote that a long time ago. I have to speculate that I didn't notice that the comparison returned False. I think I should use Mr. Wizard's way of rotating the kernel. When I make that change I will credit Mr. Wizard.
Sep
18
comment How do I evaluate only one step of an expression?
@Tangshutao, You can download the Mathematica notebook from library.wolfram.com/infocenter/MathSource/4557. It also includes a notebook of Graphics tricks, but they are quite out of date.
Aug
3
comment Problem setting up C compiler on a Mac
I evaluated that simple example. It compiles without problem, and it works. The problem is solved.
Aug
3
comment Problem setting up C compiler on a Mac
After doing that I see the clang file. Then I wrote the simple Compile function acl suggested below. It compiled without problem and it works. The problem is solved!
Aug
3
comment Problem setting up C compiler on a Mac
FileNames["/usr/bin/clang"] returns {/usr/bin/clang}. I downloaded and installed Xcode, registered with Apple as an xCode developer. I can open the xCode IDE, but there may be some other steps needed to get it working. Anyway, I thought xCode is an objective-C compiler. From what I read it sounds like you can't write a C program for OSX. It seems you have to write an objective-C program instead. However, Compile in Mathematica doesn't allow for CompilationTarget->"objective C". So what do I do next?
Jul
13
comment How to make use of Associations?
I have been a devoted Mathematica user since version 1.2, but I never picked up much CS education. As a result you always loose me when you talk about immutable, deep copy, shallow copy, bindings, semantics, etc.
Jul
13
comment Struct equivalent in Mathematica?
This comes up too often. If yo insist on using struct, program in C. If you decide to use Mathematica, read relevant portions of the documentation and you will see how the language is intended to be used. Then you should use it as Wolfram intended. You are like a Chinese person trying to use a knife and fork the same way they would use chop sticks.
Jul
13
comment Front End Find feature broken in Version 10 with OSX Mavericks?
@Szabolcs, problem is solved after holding down Sift-Command during startup. Post it as an answer and I will accept it.
Apr
24
comment Using KalmanFilter or KalmanEstimator
@bill s. I think you didn't understand what I am trying to do. I added a figure to clarify.
Apr
21
comment Using KalmanFilter or KalmanEstimator
@bill s: Thanks, but I wasn't able to find a variation of your code that does give something that resembles signalFunction@samplePoints. The first example under Applications at reference.wolfram.com/language/ref/… gives an example of doing this sort of thing. However, I don't know enough about the KalmanFilter to adapt that approach to my problem.
Apr
19
comment Using KalmanFilter or KalmanEstimator
I neglected to change [Omega]s to a number or provide a value. [Omega]s is a Symbol, not a product of symbols. That should be [Omega\s=130.0 (i.e. endpoints {130.0,188.0} )
Feb
22
comment Estimate parameters of the state space model
The function you want might be here. If that isn't what you want, go to the top of that page and look under "See Also".
Jul
21
comment Logarithmic slider
Amazing that you went so deep into undocumented functions!
Jul
13
comment Help in NIntegration Methods - Takes too long, why?
You might be able to answer your problem if you study the page here.
May
18
comment How to create internally optimized expression for computing with high WorkingPrecision?
performing arithmetic operations in the right way can reduce round off errors. One important example is use of HornerForm (a built in function) for computing polynomials. Most text books on numerical methods show a few other tricks for specific cases. It's all about avoiding catastrophic cancelation, which is the loss of precision due to subtracting numbers that are nearly equal but not close to zero.
May
18
comment How to create internally optimized expression for computing with high WorkingPrecision?
It might work better if you make jacobianMatrix a CompiledFunction. That will help if FindMinimum uses MachinePrecision to get close to the optimal solution, and switch to higher precision for fine tuning.
Jan
31
comment What are the use cases for different scoping constructs?
Yet another scoping construct that I didn't see mentioned is DynamicModule.
Jan
12
comment Interactive steam tables and phase diagrams in Mathematica
For years I have wondered why Wolfram hasn't included each steam table as an InterpolatingFunction.