15,261 reputation
13087
bio website quantdec.com
location Northeastern US
age 14
visits member for 2 years, 9 months
seen Oct 18 at 15:12

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 I can be reached through (outdated but still valid) links posted on my web site.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


Nov
25
revised Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$
added 5157 characters in body
Nov
25
comment Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$
@Rojo Many thanks for making that observation. It appears something very strange is happening with ParallelMap: it frequently "loses" about 95% of the solutions compared to those found by Map. I will rewrite this answer to avoid that problem and to include better explanations of what exactly is being done.
Nov
23
answered Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$
Nov
23
reviewed Close Placing a contourPlot under and Plot3D
Nov
22
comment Dashed line with alternating colored dashes
Filling is optional...
Nov
22
answered Dashed line with alternating colored dashes
Nov
21
comment Multi-Factorial and Series with Triple-factorial terms
+1. If you follow the strategy outlined in my answer of first simplifying the coefficients, there won't be any problem: a[j_] := Evaluate [ FullSimplify[MultiFactorial[3 j, 3]/MultiFactorial[3 j + 1, 3], Assumptions -> j \[Element] Integers]] re-expresses the sum in terms of Gamma functions and you're all set.
Nov
21
comment Multi-Factorial and Series with Triple-factorial terms
@J.M. Thank you for looking at this! I made a really stupid mistake by using the wrong definition for a. This requires a different approach, which I have incorporated in an edited version. The new approach is a little weaker because it's not fully automatic and elementary, but it may still be of interest in showing how to discover useful formulas for recursively defined functions and how to prove them correct once they have been found.
Nov
21
revised Multi-Factorial and Series with Triple-factorial terms
added 1625 characters in body
Nov
21
comment Multi-Factorial and Series with Triple-factorial terms
Replacing $3$ by $k$ gives the solution $_2F_1\left[1,1,1+\frac{1}{k},x\right]$. Applying FunctionExpand for the case $k=3$ and simplifying yields $-\frac{2 \sqrt{3} \text{ArcTan}\left[1-\frac{x^{1/3}}{2 (1-x)^{1/3}},-\frac{\sqrt{3} x^{1/3}}{2 (1-x)^{1/3}}\right]-2 \text{Log}\left[1+\frac{x^{1/3}}{(1-x)^{1/3}}\right]+\text{Log}\left[1+\frac{x^{‌​2/3}-(-(-1+x) x)^{1/3}}{(1-x)^{2/3}}\right]}{6 (1-x)^{2/3} x^{1/3}}$, showing the connection with ArcTan and Log.
Nov
21
answered Multi-Factorial and Series with Triple-factorial terms
Nov
16
comment Errors in Compile
Tom, you substantially changed the question after it was answered: please don't do that! Feel free to follow up with a new question in a new thread. Consult our faq for more guidance.
Nov
16
revised Generating convex polyhedron from face planes?
added 22 characters in body
Nov
16
answered Generating convex polyhedron from face planes?
Nov
16
revised How to join each of the spheres? Or, how to make a 3D grid?
Aliased the image and realigned the code to emphasize its brevity.
Nov
16
comment How to join each of the spheres? Or, how to make a 3D grid?
+1 This looks like the simplest, most straightforward solution so far (among those that work).
Nov
15
comment How to join each of the spheres? Or, how to make a 3D grid?
Nice idea, but: (1) This is not a 3D graphic. (2) Its coordinates do not (automatically) coincide with any 2D projection of the sphere centers (although with some work they could be made to).
Nov
15
answered How to join each of the spheres? Or, how to make a 3D grid?
Nov
15
reviewed Looks OK Timing display of Graphics (Front End timing)
Nov
15
awarded  Nice Answer