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visits member for 2 years, 6 months
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Consultant (environmental stats a specialty) and teacher.


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
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 Forecast Future Stock Prices - Brownian Motion
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.