15,171 reputation
13086
bio website quantdec.com
location Northeastern US
age 14
visits member for 2 years, 8 months
seen Sep 14 at 0:52

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 I can be reached through (outdated but still valid) links posted on my web site.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.


Jan
16
comment How to check if a 3D point is in a planar polygon?
@Rainer Assuming the points are very close to coplanar, the smallest eigenvalue will be close to zero and much smaller than the other two. The eigenvectors associated with the other eigenvalues--that is, the first two principal components--thereby span a plane passing close to most of the points. This gives two solutions: (1) The cross product of the first two principal components will be a normal vector for that plane. (2) The third principal component will be orthogonal to the other two, whence it too is a normal vector for the plane.
Nov
7
comment NMinimize usage
@Frederik You are right: I made that typo early on and because everything worked, I did not catch it. Your suggestion $x = 1+y^2$ accomplishes what was intended and everything goes through as planned. Thank you for reading this post so carefully and well!
Nov
7
awarded  Nice Answer
Oct
24
comment Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$
@xzczd Thank you! That is a useful insight and looks to be a likely explanation for the failure.
Oct
5
awarded  Nice Answer
Aug
24
awarded  Good Answer
Aug
3
awarded  Nice Answer
Jul
6
awarded  Nice Answer
Jun
12
awarded  Good Answer
Jun
11
awarded  Enlightened
Jun
11
awarded  Nice Answer
May
24
comment AstronomicalData and Planetary Heliocentric (x,y,z) Velocity Components
+1 Consider a central difference instead: it should be more accurate. It makes a substantial difference, by the way: it affects the third sig. fig. in your example, because it reflects the net planetary acceleration during the course of 12 hours.
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