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visits member for 2 years, 8 months
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Oct
24
comment A possible bug with regard to DateObjects in Version 10?
@Square1 Thank you, that seems to indeed resolve the issue which is a definite bug then. With regard to overhead it also seems to pays off to use DateList-form to generate a DateRanges and then Map DateObject to the result.
Oct
24
comment How can I plot a list of 1-D data along the x-axis?
If you do not want to show the data development over time you might consider Histogram[ data, number of data points ] which will also show the outliers that might be hidden in Plot-derivatices?
Oct
24
comment A possible bug with regard to DateObjects in Version 10?
I have not loaded anything consciously besides starting Mma 10. Note, that the code (as shown) will work on my machine without any problems at first; the problem will arise after some time only.
Oct
2
comment Building up functions from data
args = Map[ ToExpression[# <> "_"] &, myList]; f[Sequence@@args] := Evaluate[ First@args[[1]] ] seems to do the job also.
Dec
22
comment Using a different version of R with RLink on Windows 7
@Szabolcs That works fine as I just tested following your post. I seems to be an issue with releases 3.x.x of R as this thread indicates maybe: RLink and R v3.0.1?
Dec
22
comment RLink and R v3.0.1?
I have just installed R Version 3.0.2 and then tried to Install that version using InstallR["RHomeLocation" -> "C:\\Program Files\\R"] only to get the following error message: InstallR::nopaclet: Could not find RLink runtime installed. Please use RLinkResourcesInstall to install it>>. Is that (still) the same issue?
Dec
22
comment Using a different version of R with RLink on Windows 7
Unfortunately for some reason that solution does not work on my machine with Windows 7. I had just installed R from a mirror site and given the proposed InstallR["RHomeLocation" -> "C:\\Program Files\\R"] only to receive the follwing error message: InstallR::nopaclet: Could not find RLink runtime installed. Please use RLinkResourcesInstall to install it. How can that be?
Dec
19
comment Keep data in memory inside a notebook without having to evaluate it again
You might take a look at the option SaveDefinitions->True with Manipulate or at DynamicModule as these should address your problem.
Nov
25
comment How can multiple null terminated strings be handled in a DLL-function result?
Thanks a lot, Todd, that pretty much looks like THE answer to the problem. For completeness I will also point out a solution using the DLL function "vensim_get_substring" which Ventana posted on the Vensim Forum: vensim.com/documentation/index.html?26210.htm
May
29
comment NDSolve: methods and step size choosing
@Albert: Certainly not. But how many people will have read through the books by Hairer et al. - of which I spot at least three? ;-)
May
29
comment NDSolve: methods and step size choosing
Have you had a look at the complete tutorial Advanced Numerical Differential Equation Solving in Mathematica? I believe your questions are being answered there albeit it may take some reading time.
May
27
comment Inverting a Spline-Function (Bezier or BSpline)
For completeness: Surprisingly using InverseFunction with an InterpolatedFunction turns out to be slower than the indicated FindRoot- solution. But since there should be some symmetry here, I simply switched the $(x,y)$ pairs for the reference points to be $(y,x)$ pairs before letting Interpolation with Order 2 and Spline-Method find a solution. Using the thus obtained InterpolationFunction is as fast as can be wished for.
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
I just tested the FindRoot-Solution vs. using InverseFunctionon an interpolated Function as suggested in the solution on 10000 random values. It surprised me quite a bit to find the FindRoot-solution turning out faster (4.7 secs vs. 6.9 secs).
May
24
comment How can i get the solution of complicated equation?
Justed added the code using OCR.
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
That is a reasonable suggestion but since I am a bit "clueless" about which functional form to use - and what the implication of it would be - I thought "that is exactly what splines were invented for"?
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
My problem is, that besides the point $(\alpha,\beta)$ where both parameters are to be estimated, and the points $(0,0)$ and $(x_\text{max},y_\text{max})$ I do not know anything else. Interpolation[] will give a function passing through the points. I find it very hard to keep it within plausible ranges?
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
Great, thanks. You said "if you absolutely must use B-splines" -- well I need to 'calibrate' a transformation where I do not know the mapping (function) to use. From some reasonable assumptions (all values within $[0,\infty($, the function probably not beeing s-shaped etc., I found a spline to be the best way to define a smooth function with just two parameters (next to one for scaling the maximum value). What else to use/do?
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
That is interesting and a bit weird at the same time. I had tried defining a pure function (e.g. g = Last[#]&) and then using Composition[g,f][t] in the equation definition but that did not work out. I am not quite getting why the delayed function does help here?
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
@BoLe Uups, you are right, I should have used Last instead of First in my post here and so you are correct. But that still does not change the principle problem with equation solving. Thanks for pointing out the error, I will edit my question.
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
I tried FindRoot (e.g. FindRoot[First@f[t]==0.6,{t,0.5}]) but I still get the wrong result doing so?