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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.


2d
answered Mathematica style guide?
Jan
26
comment Brevity of denoting Conjugate[]
If you use David Park's Presentations add on (home.comcast.net/~djmpark/DrawGraphicsPage.html), the command ComplexConjugateDisplay[True] will automatically cause the overbar to appear in output for conjugates.
Jan
19
awarded  Popular Question
Jan
18
awarded  Yearling
Jan
11
asked How make first automatic numbering cell for a style number 1 not 0?
Jan
7
comment Awful styling in MMA10's Plot
I'm not seeing the font-spacing problem when with Mathematica 10.0.1 under Mac OS X 10.9.5 I export to EPS, even without font-embedding, and when I view the exported file in either GhostView for Mac or Graphic Converter. In each app, I do believe I'm directly viewing the EPS and not a conversion to PDF.
Jan
4
comment Associativity of `/@`
Does the Documentation Center page tutorial/OperatorInputForms, with its listing in order of precedence, help?
Jan
1
comment Initial value problem with Laplace transform
A solution was accepted in which the right-hand side $f(t)$ of the differential equation has value $t^2$ for $0 \leq t <1$ rather than, as originally requested, for $-1 < t < 0$. Should the question be edited accordingly?
Dec
27
comment Plotting piecewise functions
I should have searched before asking; this was already asked and answered at mathematica.stackexchange.com/questions/1128/….
Dec
27
comment Plotting piecewise functions
What's the easiest way, in the context of this solution, to have Mathematica automatically color the various pieces different colors -- much as would happen with a simple Plot[{f1x, f2x, ..., fnx}, {x, a, b}] expression -- without providing an explicit list of colors in a PlotStyle option?
Dec
17
comment Incorporating the minimum and maximum of the function in a Dynamic plot
Don't know whether this helps (or you already realize it): the second argument to DynamicModule could be a compound expression with components separated by semicolons. So you could end the compound expression with your Column expression and begin it with as many expressions as you need to find the min and max.
Dec
12
asked EquationTrekker PropertyValue errors
Dec
12
comment Mathematica 10 cannot solve definite integral
Seems to be OK in 10.0.2.
Dec
7
comment Get inverse of a matrix step-by-step
But LinearSolve doesn't show the process step-by-step, as the original question specified.
Dec
7
comment Evaluating the real part of an expression
To directly answer the question as asked: Mathematica has no way of knowing that you intend the symbolic entities $\chi$, $\omega$, and $\tau$ to be real; without further information, such entities might be complex.
Dec
7
comment Get inverse of a matrix step-by-step
I don't think that's the sort of "step-by-step" method the original question had in mind.
Dec
7
comment Get inverse of a matrix step-by-step
For any but the smallest order matrices, using the cofactor method is a computationally inefficient way to find matrix inverses.
Dec
7
comment Get inverse of a matrix step-by-step
I forgot to mention another auxiliary function to define on the way to constructing a program to find matrix inverses: one that adjoins to a given (square) matrix an identity matrix of the same shape. Moreover, you can make the process even fancier - and more realistic - by using scaled partial pivoting.
Dec
6
comment Get inverse of a matrix step-by-step
As @Michael E2 suggests, it's a very good exercise for Mathematica novices to write little functions that implement the 3 elementary row operations: scaling a matrix row, adding one matrix row to another, and interchanging two matrix rows. Then write a longer function that calls those functions in order to reduce a matrix to a reduced row echelon form. If the entries are going to be numeric, you'll want a function to round to 0 exactly entries that are sufficiently small. For more practical results, write and call a function that does partial pivoting.
Dec
6
awarded  Popular Question