7.16 Tuesday, September 16, 2014
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Top new questions this week:
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[How many triangles are
there?]\url{http://mathematica.stackexchange.com/questions/59350/how-many-t
riangles-are-there}
Some time ago I found a puzzle and it stopped my work until I solved it.
One of the possible solutions:
Let us sum upright and upside down triangles whose top lies in the
$i$-th row.
$$
...
- asked by ybeltukov (22 votes), answered by george2079 (20 votes)
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[Composition a la Mondrian]
\url{http://mathematica.stackexchange.com/questions/59620/composition-a-la-mondrian}
I would like to paint something like this
or,even better, like this
I have tried
colors =
{Red, Blue, Yellow, White, Black};
cells =
ConstantImage[RandomChoice[colors], #] & /@
...
- asked by eldo (21 votes), answered by Simon Woods (11 votes)
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[Homotopy
Visualization]\url{http://mathematica.stackexchange.com/questions/59463/hom
otopy-visualization}
I noticed that both the lower cased 'i' and the Apple logo are
topologically equivalent to the disjoint union of two closed discs.
I'd like to animate a homeomorphism from the left to the right, ...
- asked by Tobi Lehman (18 votes), answered by Michael E2 (28 votes)
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[Finding all paths of certain length between vertices in path graph,
non-simple ones
too]\url{http://mathematica.stackexchange.com/questions/59554/finding-all-p
aths-of-certain-length-between-vertices-in-path-graph-non-simple-o}
First I will tell you what my ultimate goal is, because maybe there's
another way of doing it other than what I am trying.
I need a list of all $(a_1, a_2, \ldots, a_N)$ tuples that satisfy
certain ...
- asked by luke (12 votes), answered by ybeltukov (7 votes)
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[How to manipulate a circle in GeoGebra
style?]\url{http://mathematica.stackexchange.com/questions/59726/how-to-man
ipulate-a-circle-in-geogebra-style}
I want to emulate the GeoGebra app. I want to get an effect like this in
Mathematica.
I don't know how to move whole circle without changing the radius of the
circle.
My sample code:
...
- asked by mathe (11 votes), answered by Kuba (5 votes)
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[Splitting strings into letter keys and
integers]\url{http://mathematica.stackexchange.com/questions/59690/splittin
g-strings-into-letter-keys-and-integers}
I have strings of the following form:
string = "ABC123DEFG456HI89UZXX1";
Letter keys of variable lengths are followed by (positive) integers.
I want to get this transformation:
{{"ABC", 123}, ...
- asked by eldo (11 votes), answered by RunnyKine (10 votes)
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[Mathematica isn't sure whether a sum of two positives is positive or
not]\url{http://mathematica.stackexchange.com/questions/59589/mathematica-i
snt-sure-whether-a-sum-of-two-positives-is-positive-or-not}
Mathematica is not able to tell whether a summation of two positive
expressions is positive or not. Which is very strange.
My three symbolic arguments, $x$, $y$, and $z$, are all real numbers
bounded ...
- asked by jim (10 votes), answered by Jens (9 votes)
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Greatest hits from previous weeks:
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[Generating visually pleasing circle
packs]\url{http://mathematica.stackexchange.com/questions/40334/generating-
visually-pleasing-circle-packs}
EDIT: I want to thank you all guys for this unexpected intellectual and
artistic journey. Hope you enjoyed as I did.
I would like to generate a circle pack that mimics this: (don't pay
attention on ...
- asked by VividD (62 votes), answered by level1807 (39 votes)
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[Finding real roots of negative numbers (for example,
$\sqrt[3]{-8}$)]\url{http://mathematica.stackexchange.com/questions/3886/fi
nding-real-roots-of-negative-numbers-for-example-sqrt3-8}
Say I want to quickly calculate $\sqrt[3]{-8}$, to which the most
obvious solution is $-2$.
When I input $\sqrt[3]{-8}$ or Power[-8, 3^-1], Mathematica gives the
result "$2 (-1)^{1/3}$". Not what I ...
- asked by jtbandes (33 votes), answered by Brett Champion (13 votes)
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Can you answer these?
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[NIntegrate::ncvbr: How should we interpret and handle this error not
mentioned in any
documentation?]\url{http://mathematica.stackexchange.com/questions/59371/ni
ntegratencvbr-how-should-we-interpret-and-handle-this-error-not-mentione
d-i}
I have some user-defined module describing my integrand which has to be
computed numerically (it's much more complicated than this but bear with
me):
foo[x_?NumericQ, y_?NumericQ, z_?NumericQ] := ...
- asked by Sarah (3 votes)
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[How can I solve an equation where indexed variables get updated during
iteration?]\url{http://mathematica.stackexchange.com/questions/59776/how-ca
n-i-solve-an-equation-where-indexed-variables-get-updated-during-iterati
on}
I am trying to solve for a root for a certain equation, but some of the
variables in this equation are indexed and get updated during iteration.
The code that I am interested in is like the following:
...
- asked by erickwy (1 vote)
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[Generalize WASD Function First Person
Viewing]\url{http://mathematica.stackexchange.com/questions/59655/generaliz
e-wasd-function-first-person-viewing}
How might I generalize the following WASD question such that it works
with any Graphics3D object and includes q and e for z(up and down)
movement? For example qweasd[gr_].
In addition, how might I ...
- asked by Liam William (2 votes)