Search found 67 matches

by Glen
Sun Dec 16, 2012 11:58 pm
Forum: Mathematics
Topic: Determinant for V = 12h³ - 6ah² + ha²
Replies: 3
Views: 8009

Re: Determinant for V = 12h³ - 6ah² + ha²

Hi Jason That determinant seems to be V = 12h³ - 6ah + ha² Unfortunately, the equation is V = 12h³ - 6ah² + ha² (--- note middle term is a little different) A comment in Hall seems to suggest that without a common factor (as there is in the first one), 3-terms in two RHS variables usually doesn't wo...
by Glen
Sat Dec 15, 2012 4:35 pm
Forum: Mathematics
Topic: Determinant for V = 12h³ - 6ah² + ha²
Replies: 3
Views: 8009

Determinant for V = 12h³ - 6ah² + ha²

Spotted the question here: http://math.stackexchange.com/questions/141112/determinant-form-of-equation-3-variables-third-order-nomogram I can see how to do this much: -V + 12h³ - 6ah² easily enough, and probably any two of the terms on the RHS can be done the same way. This doesn't look like it's ne...
by Glen
Fri Dec 14, 2012 2:43 pm
Forum: Mathematics
Topic: Req: Can this eqn be expressed in Std Nomo Form?
Replies: 22
Views: 36285

Re: Req: Can this eqn be expressed in Std Nomo Form?

> Is it possible to use PyNomo to draft compound curved nomograms of this type? If you take a look at this document: http://www.myreckonings.com/pynomo/CreatingNomogramsWithPynomo.pdf and check out p56, 63, 66, 72, it definitely looks like single-curved-scale nomograms and compound nomograpms can bo...
by Glen
Fri Dec 14, 2012 2:40 pm
Forum: Mathematics
Topic: Req: Can this eqn be expressed in Std Nomo Form?
Replies: 22
Views: 36285

Re: Req: Can this eqn be expressed in Std Nomo Form?

[This got posted early accidentally and ended up with some stray lines. I deleted the mangled text and reposted below. If I figure out how to delete this, I will.]
by Glen
Mon Dec 10, 2012 6:38 am
Forum: Mathematics
Topic: Req: Can this eqn be expressed in Std Nomo Form?
Replies: 22
Views: 36285

Re: Req: Can this eqn be expressed in Std Nomo Form?

This can be done without contours/grid, just a pair of three scale nomograms with a common scale (compound nomogram)... but one scale is curved. Nomo 1: t = y.v done with an N scale where y is one of the straight-side scales. Nomo2: y = u/w (1 - 0.5(w - u)) (u scale is curved, w scale is straight, y...
by Glen
Tue Feb 07, 2012 2:28 am
Forum: Software
Topic: UseR talk, fitting a nomo equation in R (drawn in PyNomo)
Replies: 1
Views: 17012

UseR talk, fitting a nomo equation in R (drawn in PyNomo)

Wasn't sure whether to post this here or in General. At last year's UseR! conference, Johnathan Rougier presented a talk on making (and using) nomograms to estimate weights of donkeys in Africa (on joint work with Kate Milner). He fitted models to data in R (using Box-Cox transformations, something ...
by Glen
Fri Jan 20, 2012 9:39 am
Forum: Mathematics
Topic: Nomogram for 5 variables
Replies: 12
Views: 22241

Re: Nomogram for 5 variables

I don't suppose this is much use to you now, but looking at this equation: starting with the version of your equation where you had Q = er1^2/(lr1^2 - lr2^2) let L = l (for clarity; l can look like 1) Let R2 = r2^2 and R1 = r1^2 for ease of manipulation - just label the axes with the values of r1 an...
by Glen
Thu Jan 19, 2012 9:26 am
Forum: General
Topic: The Posographe
Replies: 1
Views: 6580

The Posographe

Take a look at this amazing old device: http://www.nzeldes.com/HOC/Posographe.htm If anyone has any pointers to the mathematics of this kind of device, I'd love to know about it I guess it would be quite feasible to work out how to make them eventually, but it looks like a lot of work to figure out.
by Glen
Wed Dec 08, 2010 6:11 am
Forum: Software
Topic: Using R to create/draw nomograms
Replies: 3
Views: 12988

Re: Using R to create/draw nomograms

[quote="ScottF"]Glen, Are there any updates on your attempt to use R?[/quote] Wow, I didn't think anyone was interested. I did a little more, but I guess I ran down some side alleys since then. Besides spending a lot more time learning R, I've been playing a little with making slide rules/...
by Glen
Fri May 28, 2010 3:48 am
Forum: General
Topic: A somewhat nifty slide rule
Replies: 0
Views: 8396

A somewhat nifty slide rule

A normal-distribution slide rule at statpics blog
by Glen
Thu Mar 04, 2010 8:25 am
Forum: Literature
Topic: Trouble finding an algorithm
Replies: 9
Views: 16942

Re: Trouble finding an algorithm

Hi Joe, thanks for that. I'm reasonably familiar with quasi-Newton methods; I studied them during my computing major (years ago), and they're used in a variety of problems I work with. They're sometimes used in statistics; we were even discussing them in a seminar I was at a few weeks ago. Indeed, Q...
by Glen
Thu Feb 25, 2010 4:19 am
Forum: Literature
Topic: Trouble finding an algorithm
Replies: 9
Views: 16942

Re: Trouble finding an algorithm

So this is actually an optimization problem: which algorithm to use to fit data for a given or guessed function. Least squares is of course only one choice. For me using python, I would hope to find a ready algorithm in: http://docs.scipy.org/doc/scipy/reference/optimize.html Minimizing maximum err...
by Glen
Tue Feb 23, 2010 1:52 am
Forum: Literature
Topic: Trouble finding an algorithm
Replies: 9
Views: 16942

Re: Trouble finding an algorithm

Would't any curve fitting algorithm work? If one has a function and data, curve fitting finds best match with given error function. For example least-squares fitting. Computers in general use are quite new in perspective of nomography. So are these question practical or kind of academic? I am attem...
by Glen
Tue Feb 16, 2010 5:14 am
Forum: Software
Topic: Fitting nomograms to data
Replies: 1
Views: 7964

Genus II - Re: Fitting nomograms to data

I believe I have come up with a simple algorithm for fitting Genus II nomograms to data, given an algorithm for fitting genus 0 nomograms with weights (which I believe I already have). At least simple relative to what I thought would be involved. I will need to do some testing, and checking that it ...
by Glen
Sat Feb 13, 2010 12:05 am
Forum: Literature
Topic: Trouble finding an algorithm
Replies: 9
Views: 16942

Re: Trouble finding an algorithm

I wouldn't wish you to make a special trip on my account, though next time you happen to be around the right area(s), it would be great if you could take a look. Besides the de Boor book that I linked to above Approximation theory By Carl De Boor, American Mathematical Society (near p77) (where the ...

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