15,421 reputation
13189
bio website quantdec.com
location Northeastern US
age 14
visits member for 3 years
seen Jan 23 at 23:34

Consultant (environmental and spatial stats a specialty), expert witness, and teacher. I can be reached through (outdated but still valid) links posted on my web site.

Twitter: @WilliamAHuber // ASA-P website: http://amstatphilly.org/


Why waste time learning, when ignorance is instantaneous?

--T(iger) Hobbes.

For any complex problem there is a simple solution. And it's always wrong.

--[Mis?]attributed to H.L. Mencken by Dava Sobel, Longitude.


May
24
comment How to calculate the volume of a convex hull?
That doesn't quite seem to be a duplicate, @andre, because there the data are given in a different form. In principle there should be a formula for computing the volume in terms of a suitable integrals over the curve.
May
24
awarded  Nice Answer
May
23
comment Finding integral points on a surface
The equation is a cubic (parameterized by $n$), so it's possible a more efficient method to obtain all solutions can be found by computing generators of its group of integral points. But typically these groups are so small--I haven't found one larger than $12$ yet--as a practical matter it might not be worth the effort.
May
23
revised Finding integral points on a surface
added 12 characters in body
May
23
revised Finding integral points on a surface
added 217 characters in body
May
23
comment Finding integral points on a surface
You're welcome. You shouldn't be so quick to accept this answer, though: this community does a great job of improving answers over the course of a day or two. Much better answers might appear soon :-).
May
23
revised Finding integral points on a surface
added 935 characters in body
May
23
answered Finding integral points on a surface
May
22
comment CorrelationTest small bug?
It seems to me they are testing the same hypotheses but are using different approximations to the sampling distribution of the test statistic.
May
22
comment Composition: how to make a day and night world map?
This question also has an answer (using MMA illustrations) on the GIS site.
May
22
reviewed Close How to estimate system recource usage of a SparseArray?
May
21
comment How can I detect an ellipse in a photo?
+1 That's a real tour de force, beautifully described. Impressive.
May
21
comment Unexpected behavior of confidence bands for data presenting two regions with uneven noise
Heteroscedasticity can be complicated: no longer does it suffice to stipulate that all residuals have the same variance, so now you need a model not only for the data values, but also an equally complicated one for the variances of their residuals. You're in the realm of highly specialized coding. If you know what you're doing, MMA is a great platform for writing that code; otherwise, look to specialized platforms like R and hope someone has contributed a model that might be appropriate for your situation.
May
21
comment Speeding up a numerical constrained quadratic optimization
@OleksandrR's suggestion to use a quadratic programming solution typically requires 0.02 seconds or less when applied to problems of the same size having random coefficients.
May
21
comment How can I detect an ellipse in a photo?
Substantial progress towards a solution can be found by reviewing these related posts. A Hough transform looks attractive.
May
20
comment Problem with the Plot of Functions and PlotLegends
What specifically is wrong with the output?
May
20
comment Solar System Orbital Parameters
Just in case you are interested in accuracy, it might be worth noting that the system of ODEs described in your previous question at mathematica.stackexchange.com/questions/25039/… is not what is usually meant by an "n-body simulation," because it does not account for interactions among the bodies: it's just a collection of independent central field solutions. It might be a fine approximation for times close to the initial time but will be observably incorrect.
May
20
comment Find all the integer numbers $a$, $b$, $c$, $d$, $e$, $f$, $k$ to this equation have three integer different solutions?
The question, which evidently is missing several words, now reads as if you are asking for all integral values of $a,\ldots,k$ in the interval $[-10,10]$ for which your equation has three distinct integral solutions. Is this a correct interpretation?
May
18
reviewed Close Generating a list of all factorizations
May
18
reviewed Leave Open Strange Behavior of NDSolve