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visits member for 2 years, 6 months
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I'm a retired mathematics professor who's used numerous programming languages over the years, including FORTRAN, Pascal, and APL. My current programming interests are Mathematica and J (the jsoftware.com free product), both of which I've used in teaching.


3h
comment Is there a way to recreate the typical Red/Blue-Postereffect using Mathematica?
+1 for choice of image!
4h
comment Computational complexity of symbolic determinant
Documentation Center page tutorial/SomeNotesOnInternalImplementation#7441 says, "Det uses direct cofactor expansion for small matrices and Gaussian elimination for larger ones."
4h
comment Mathematica 10 : Where is the Mathematica Book?
Same thing is in the in-application tutorial/VirtualBookOverview. But how can one add a link to this on the Mathematica 10 Help menu or, better, an icon link on the Documentation Center home page?
Jul
21
comment Easiest Way to Use ShowGroupOpener in Mathematica
@Ben Allgeier: Right! You apply the GroupOpener to the Input/Output group after you evaluate the Input cell. If you double-click the Output cell it hides the Input cell but leaves the GroupOpener on the Output cell. But then when you open the group, the GroupOpener appears as if on the Input cell -- really on the whole group, which always means the first cell within the group. Thus this seems to achieve what you originally asked: display only the Output but have the GroupOpener displayed as a way to display the Input too.
Jul
21
comment Easiest Way to Use ShowGroupOpener in Mathematica
@Ben Allgeier: Which version of Mathematica are you using? I'm using 10.
Jul
19
comment Easiest Way to Use ShowGroupOpener in Mathematica
Apply the ShowGroupOpener option to the (evaluated) Input cell. Then double-click the Output cell; that will close the group, leaving just the Output cell visible. But the GroupOpener will now appear on that Output cell. When you open the group, the GroupOpener will instead appear on the Input cell.
Jul
17
comment Backward compatibility for plugins
It depends on the particular plugin. Check with the plugin's author or publisher.
Jul
16
comment Version 10 of Mathematica in Windows XP
Microsoft itself no longer supports Windows XP, so why expect new Wolfram products work with it?
Jul
9
comment Implementing efficient multiple undo
Now that Mathematica 10 has been released, note that among new features is: "Computation-aware multiple undo The problem of multiple undo in Mathematica has been solved!". See wolfram.com/mathematica/new-in-10/for-existing-users.
Jul
6
comment Plotting a multivariable function
I was going to down-vote this since it would seem to be a very simple error that would be avoided by just looking at the documentation for Plot3D. Turns out, though, that it's not so easy to find an example in the documentation like this, where first one defines the function of two variables and then plots it. (The first example there of this kind is, in fact, much more complicated: NDSolve[{D[u[t, x], t] == D[u[t, x], x, x], u[0, x] == 0, u[t, 0] == Sin[t], u[t, 5] == 0}, u, {t, 0, 10}, {x, 0, 5}] followed by what is essentially Plot3D[Evaluate[u[t, x] /. %], {t, 0, 10}, {x, 0, 5}].
Jul
2
awarded  Curious
Jul
1
comment “not a list of numbers” and “cannot be used for replacing ”
For different colored curves, wrap the first argument of the Plot expression with Evaluate[...].
Jun
29
comment Kernel quits upon evaluation of a limit
In Mathematica 9.0.1 under OS X 10.9.3, I don't get a crash; as output I just get the original limit unevaluated.
Jun
29
comment Kernel quits upon evaluation of a limit
In Mathematica Programming Cloud, hence presumably in forthcoming Mathematica 10, Limit[(1 + t/Sqrt[n])^-n, n -> Infinity] just returns unevaluated without crashing. Adding Assumptions -> t > 0 gives limit 0; t < 0 gives limit Infinity; and of course t == 0 gives limit 1.
Jun
27
comment Which functions automatically generate new functions?
@Szabolcs: Yes, such examples as indicated in these comments indicate greater availability of such built-in functions. It's so much nicer, e.g., to use such functions in Postfix notation than to construct a corresponding pure functions. E.g., ints = RandomInteger[{2, 100}, 50]; ints // Select[PrimeQ] rather than ints // Select[#, PrimeQ] &.
Jun
27
comment Which functions automatically generate new functions?
@Oleksandr R.: Yes, I'm aware that one can define such function-generating functions as a user; in fact, I have certainly done so because it's such a useful thing in some situations. That's why I was looking for more built-in functions of this type.
Jun
27
comment Which functions automatically generate new functions?
@Szabolcs: Except for Derivative, I didn't recall other built-in functions that produce functions as output; nor built-in functions that, if one omits trailing arguments, yield functions as output. Such functionality is powerful, so I want to find out about other examples.
Jun
26
asked Which functions automatically generate new functions?
Jun
26
comment What is the relationship between Mathematica and Wolfram Desktop?
I have the uncomfortable feeling that, for some potential customers, choosing a Wolfram product will be like choosing within the line of one brand of dishwasher detergent: lemon scented, unscented, regular, high-efficiency, with added bleach, with added drying agent, etc. My own tendency when confronted with so many choices is to just run away.
Jun
26
comment What is the relationship between Mathematica and Wolfram Desktop?
After reading here and on the Wolfram site, it's clear that WRI has done a really poor job in explicating the differences between, and the relationships among, all these new and old products.