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seen Jun 24 '13 at 0:02

No, his mind is not for rent
to any god or government.
Always hopeful, yet discontent.
He knows changes aren't permanent,
but change is.

— Rush, Tom Sawyer


Taking an externally-imposed and much-needed break from SE activities.

E-mail (flipped ROT13): zqd˙ʎʌuzʇ@ʇɐʌǝɥʇʌssqɹǝɥɟuɹʎɔ
Any code I've posted here I place under the WTFPL.


Aug
18
awarded  Necromancer
Aug
18
awarded  Nice Answer
Aug
16
awarded  Popular Question
Jul
3
awarded  Nice Question
Jun
23
comment Excel column label from integer
To clarify: if, say, the function is named spreadsheetColumn[], then spreadsheetColumn[27] should return "AA"?
Jun
23
comment How to choose three points on the circle so that the triangle is not a right triangle?
Maybe include Circle[{-2, -1}, 5] too, to facilitate visualization.
Jun
23
comment Solving this system of equations produces an error message about badly conditioned matrix
You'll want to look at Eigensystem[].
Jun
23
comment Measuring the area of non analytical regions in a plot
I don't see you mentioning your "different reasons"; if you have the points comprising your curves, you can at the very least use the "shoelace formula" or fancier methods to get a good estimate of the area.
Jun
23
revised How to choose three points on the circle so that the triangle is not a right triangle?
edited tags
Jun
23
revised Malliavin Derivative with Mathematica is it possible?
edited tags
Jun
23
comment Numerical Integration with InverseErfc
This is an answer, but apparently not for this question.
Jun
23
revised Numerical Integration with InverseErfc
edited tags
Jun
22
revised I can't understand FindShortest Tour
edited tags; edited tags
Jun
22
comment Line perpendicular to a tangent line to a parabola behaves unexpectedly
Of course it will stretch quite a bit; your setting PlotRange -> {0, 100} is hella huge. The thing is, with the default AspectRatio setting, you just won't see lines that are supposed to be perpendicular as actually perpendicular, and the Automatic setting fixes that. See Jens's answer as well.
Jun
22
comment Line perpendicular to a tangent line to a parabola behaves unexpectedly
Add AspectRatio -> Automatic and report back.
Jun
22
comment Trace of FullSimplify
"if it is possible for Mathematica to show the steps" - not in this case, I believe.
Jun
22
comment Trace of FullSimplify
In general, the simplification methods internally used by Mathematica do not necessarily correspond to how one might simplify by hand; remember that a method that is simple for computers to do is not necessarily simple for humans, and vice-versa.
Jun
22
comment How to maximize a function over a rotation matrix?
I don't have Mathematica on me at the moment, but you might try {Array[K, {3, 3}], {p, q, r}, a, b} /. Last[NMinimize[Flatten[{Total[MapThread[SquaredEuclideanDistance, {f[#, Array[K, {3, 3}], {p, q, r}, a, b] & /@ x, y}]], Thread /@ Thread[Transpose[Array[K, {3, 3}]].Array[K, {3, 3}] == IdentityMatrix[3]], Det[Array[K, {3, 3}]] == 1, a > 0, b > 0}], Flatten[{Array[K, {3, 3}], {p, q, r}, a, b}]]]...
Jun
22
comment How to maximize a function over a rotation matrix?
...and some example points would be, y'know, cool too...
Jun
22
comment How to maximize a function over a rotation matrix?
Some more definiteness would be appreciated; in particular, what would your $f$ typically look like?