dhbnumerics-discussion — Discussion

[Dhbnumerics-discussion] Code for spline differentiation

[d p. <mr....@gm...>]

!DhbNumericalMethodsTestCase methodsFor: 'functionEvaluation' !
 
testSplineDifferentiation
"
self debug: #testSplineDifferentiation
"
	| interval testInterval interpolator |
	interval := 0.0 to: 10.0 by: 0.1.
	testInterval := 1.0 to: 9.0 by: 0.05.
	interpolator := DhbSplineInterpolator new.
	interval do: [:x | interpolator add: x @ x sin].
	testInterval do: [:x | self assert: (x cos - (interpolator
valueDerivative: x)) abs < 1.0e-6]! !



!DhbSplineInterpolator methodsFor: 'information' !
  
valueDerivative: aNumber 
"needs a trivial refactoring with #value to remove identical code"
	| answer n1 n2 n step a b  constantTerm aTerm bTerm |
	coefficients isNil ifTrue: [self computeSecondDerivatives].
	n2 := pointCollection size.
	n1 := 1.
	[n2 - n1 > 1] whileTrue: 
			[n := (n1 + n2) // 2.
			(self xPointAt: n) > aNumber ifTrue: [n2 := n] ifFalse: [n1 := n]].
	step := (self xPointAt: n2) - (self xPointAt: n1).
	a := ((self xPointAt: n2) - aNumber) / step.
	b := (aNumber - (self xPointAt: n1)) / step.
	constantTerm := ((self yPointAt: n2)  - (self yPointAt: n1)) / step. 
	aTerm := (coefficients at: n1) * (1 - (3 * a squared)) * step / 6 .
	bTerm := (coefficients at: n2) * (1 - (3 * b squared)) * step / 6 . 
	^ constantTerm + aTerm - bTerm. 
	! !

Re: [Dhbnumerics-discussion] New bits of source code

[Adriaan v. O. <av...@xs...>]

Daniel,

Sure.

Either publish it at Cincom Open Repository (prefered) or send me the code.

Thx.

Adriaan.


> Hi
>
> Weve added a method onto DhBSplineInterpolator to answer the
> diferential of a function at a point. Do you want the test & code for
> it?
>
> Regards
>
> Daniel
>
>
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-- 
http://vdg38bis.xs4all.nl

[Dhbnumerics-discussion] New bits of source code

[d p. <mr....@gm...>]

Hi

Weve added a method onto DhBSplineInterpolator to answer the
diferential of a function at a point. Do you want the test & code for
it?

Regards

Daniel

[Dhbnumerics-discussion] FASD project: Online survey launched

[<ben...@id...>]

Dear Open Source developer

I am doing a research project on "Fun and Software Development" in which I kindly invite you to participate.
You will find the online survey under http://fasd.ethz.ch/qsf/. The questionnaire consists of 53 questions and you will need about 15 minutes to complete it.

With the FASD project (Fun and Software Development) we want to define the motivational significance of fun when software developers decide to engage in Open Source projects. What is special about our research project is that a similar survey is planned with software developers in commercial firms. This procedure allows the immediate comparison between the involved individuals and the conditions of production of these two development models. Thus we hope to obtain substantial new insights to the phenomenon of Open Source Development.


With many thanks for your participation,
Benno Luthiger


PS:
The results of the survey will be published under http://www.isu.unizh.ch/fuehrung/blprojects/FASD/.
We have set up the mailing list fa...@we... for this study. Please see http://fasd.ethz.ch/qsf/mailinglist_en.html for registration to this mailing list.

_______________________________________________________________________

Benno Luthiger
Swiss Federal Institute of Technology Zurich
8092 Zurich

Mail: benno.luthiger(at)id.ethz.ch
_______________________________________________________________________

[Dhbnumerics-discussion] vector equations

[Alexey S. <le...@us...>]

Hi.

I've got just a quick question.
Is it possible to solve system of equations with NewtonZeroFinder? To
pass Vector as initial values and get the result vector for all
unknown variables on exit. Or it is one-dimensional function?