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| bio | website | quantdec.com |
|---|---|---|
| location | ||
| age | ||
| visits | member for | 1 year, 4 months |
| seen | 4 hours ago | |
| stats | profile views | 908 |
Consultant (environmental stats a specialty) and teacher.
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9h |
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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. |
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14h |
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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. |
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1d |
awarded | Nice Answer |
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1d |
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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. |
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1d |
revised |
Finding integral points on a surface added 12 characters in body |
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1d |
revised |
Finding integral points on a surface added 217 characters in body |
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1d |
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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 :-). |
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1d |
revised |
Finding integral points on a surface added 935 characters in body |
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1d |
answered | Finding integral points on a surface |
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2d |
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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. |
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2d |
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Composition: how to make a day and night world map? This question also has an answer (using MMA illustrations) on the GIS site. |
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2d |
reviewed | Close Forecast Future Stock Prices - Brownian Motion |
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2d |
reviewed | Close How to estimate system recource usage of a SparseArray? |
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May 21 |
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How can I detect an ellipse in a photo? +1 That's a real tour de force, beautifully described. Impressive. |
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May 21 |
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Behaviour of prediction bands 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. |
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May 21 |
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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. |
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May 21 |
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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. |
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May 20 |
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Problem with the Plot of Functions and PlotLegends What specifically is wrong with the output? |
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May 20 |
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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. |
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May 20 |
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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? |
