Texas Instruments TI-92+, Список советов

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The gamma function is included here, too. Its presence may encourage exploration of this complicated
topic during the second calculus course and will be an occasional aid to students in applied courses.
Its accuracy seems to be good beyond 5D, plenty for beginners.
“Automatic” computation of the Fourier series of a periodic function is provided by another useful
function in this utility package. It will compute a designated number of terms in the Fourier series of a
function specified on a period interval. A graph of the partial sum is displayed. This will be very useful
to those who wish to bring this important applied topic to a calculus course audience.
Five integral applications round out the Advanced portion. The first allows the evaluation of a two-fold
iterated integral over a region which is described “curve-to-curve” and “point-to-point”, what are called
Type I or Type II regions in some books. More generally, it allows the surface integral of a function over
a surface given in the form z=f(x,y), weighted by a “density function”, d(x,y). The terminology and
names used in these applications are not standard to most calculus books, but they will be somewhat
familiar to students of physics and mechanics. More general terminology and more examples would
make this more useful to students, but the function is very powerful. Another “integral of Density” for a
polar region is provided by a second function here. It simply evaluates the integral of a function of r and
theta over a “nice” region defined in polar coordinates.
The “Centroid of Density” function returns the coordinates of the centroid of a plane region in
rectangular coordinates which is weighted with a density function depending on the two rectangular
coordinate variables. And, for the same data, the “Inertia Tensor” function returns a 2X2 matrix with
entries which are the moments of inertia with respect to the two axes and the (equal) products of
inertia. This terminology is straight from a mechanics or physics book and doesn’t appear in most
calculus books., where moments of inertia _are_ discussed. (I wonder how many calculus students will
_ever_ know what an inertia tensor is?)
The last function is the curiously named “Arc Displacement” , which most calculus texts refer to as “arc
length in polar coordinates.” The function name is ‘plrArcLn( ), whch seems appropriate. Again, there is
a provision for including a weight function to “distribute” mass or charge or some other quantity along
the curve. Thus, a problem of finding the total mass of a non-uniform wire in the shape of a known
curve is facilitated.
There is a nice 40 page Acrobat manual describing the Calculus Tools package. In places it is a little
too terse for my taste. The formulas which are the basis of the functions provided are not typically
included, leaving open their exact interpretation. I ended up doing the examples by hand to convince
myself of their meaning, but some users may be buffaloed by terminology and a paucity of examples.
My complaints are thus more about the clarity of what is available than of the execution or utility of the
mathematics here. More standard terminology and a few more examples would improve this neat
addition to the TI FlashWare arsenal. This will be useful on occasion to most students and users of
calculus, and it could be very useful during a learning process involving any one of the techniques or
topics covered. I hope we see more such packages. This one was produced by a cooperative effort of
a number of the gurus of these calculators, and not by TI headquarters. Most are not mathematics
teachers. I hope that this is a precursor of similar packages to come from other users incorporating
material which they have found genuinely useful to themselves and not just included for commercial
impact.
[6.52] Return complex result in REAL mode with 0i
In general, complex results are not returned if the Complex Format mode is set to REAL. For example,
ln(- ℯ ^(x))
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