unhd (Roger Gonzalez ) (10/18/90)
I've had my '48 for a week now, and I love it! Unfortunately, some things are taking a while to get into my fingers. Please note that my last calculator was a 27S, which I loved for its simplicity (it had the same menu interface structure, and a less capable equation solver). I am finding that many of the features of the '48 are not too user friendly. Please excuse if these are FAQs, I just started subscribing today and I'm impatient :-) 1) Going from solver to plot and back to the solver. There are times that I have an equation with several variables, and would like to plot it several times with different values in the non-plotted variables. Is there an easy way to do this? It seems to take a lot of key strokes. Also, sometimes I'd like to tweak the equation a little, but I keep ending up editing the name of the function rather than the function itself. 2) Creating equations seems to fill up the VAR menu very quickly. Is this because I am creating them as global variables? In general, I am finding that I clutter up the menus and lists rapidly. Although the manuals talk about directories and such, I am not getting a clear overall view of the best ways to organize the equations, programs, constants, and whatnot that I create. Examples of how to manage the data would be appreciated! You almost need a system administrator for this thing! 3) Is the algebraic manipulator actually worth anything? I haven't investigated too closely, but it seems that it would be faster to just do it on paper before you input the equation. 4) Flag -19 seems to dictate how complex numbers are represented; in () form or in [] form. When would I want to use it in [] form? 5) Is there a good way to get a complex number input that contains a (for example) square root term as one of the numbers? I have only found two ways: build the two arguments up on the stack, and then do a 2D, or by entering the root on the stack, then the () on the command line, and then doing the interactive stack command "echo". Any better ways? 6) Is there a quick and dirty way to factor a polynomial? Have it spew out the real/complex roots? No? Drat. :-) I realize that I could probably just look this up, but I'd much rather just be lazy and leach off the net-wisdom. -Roger -- "The question of whether a computer can think is no more interesting than the question of whether a submarine can swim" - Edsgar W. Dijkstra rg@unhd.unh.edu | UNH Marine Systems Engineering Laboratory r_gonzalez@unhh.bitnet | Durham, NH 03824-3525
edp@jareth.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.)) (10/22/90)
In article <1990Oct18.135213.22920@uunet!unhd>, rg@uunet!unhd (Roger Gonzalez ) writes: >1) Going from solver to plot and back to the solver. There are times that >I have an equation with several variables, and would like to plot it several >times with different values in the non-plotted variables. Is there an easy >way to do this? You might write a little program that takes several numbers from the stack and stores them in your variables. Then you could call it between plots. Or you could write a program that stores one value, plots, stores another value, plots, and so on. >2) Creating equations seems to fill up the VAR menu very quickly. Is this >because I am creating them as global variables? I'm not sure what you mean by filling up the VAR menu. NEXT and PREV will let you step through many pages. Do you just mean you're collecting a lot of variables which makes them hard to find? To organize your directories, you might try putting a set of equations for one problem in one directory and equations for other problems in other directories. Typically, it is useful to keep all the programs and variables in one directory, although there are exceptions. One exception is when you have some things that do not change often (like basic equations) and some things that do change often (like values). Then you can put the infrequently-changing things in a parent directory and keep the changing things in a subdirectory. That cuts down clutter in the current directory. The things in the parent directory don't appear on the VAR menu. But you can make them accessible by putting them in a custom menu. Another thing to put in parent directories is things that are common to several subdirectories, such as equations that are common to several different problems. >3) Is the algebraic manipulator actually worth anything? I haven't >investigated too closely, but it seems that it would be faster to just do >it on paper before you input the equation. Generally, I do not think it is found to be very useful. It has a few nice things in it, like the definitions for trigonmetric functions in terms of exponentials. And you can use it occasionally to fiddle with a reduction or adjustment that COLCT won't make. But otherwise I don't think it gets much use. >4) Flag -19 seems to dictate how complex numbers are represented; in () >form or in [] form. When would I want to use it in [] form? Page 167 of the Owner's Manual describes the differences. "The main advantages of using complex numbers are that they are allowed as elements of vectors and matrices and that most real number operations work on them. The main disadvantages of using complex numbers are that they are limited to two dimensions and that vector operations like DOT and CROSS don't apply to them." >5) Is there a good way to get a complex number input that contains a >(for example) square root term as one of the numbers? You can type in algebraic expressions for the elements of complex numbers. Type ' to start an algebraic. For example, ' ( 2 , sqrt 9 ENTER will give you '2+sqrt(9)*i'. You can leave it in that form or use ->NUM to get (2,3). You could also enter 'real+imaginary*i' yourself. >6) Is there a quick and dirty way to factor a polynomial? Have it spew >out the real/complex roots? No? Drat. Various polynomial routines have appeared in this group. Check out the FTP sites mentioned from time to time. -- edp
ags@seaman.cc.purdue.edu (Dave Seaman) (10/23/90)
In article <1990Oct18.135213.22920@uunet!unhd> rg@unhd.unh.edu (Roger Gonzalez ) writes: >1) Going from solver to plot and back to the solver. There are times that >I have an equation with several variables, and would like to plot it several >times with different values in the non-plotted variables. Is there an easy >way to do this? It seems to take a lot of key strokes. Also, sometimes I'd >like to tweak the equation a little, but I keep ending up editing the name of >the function rather than the function itself. Provided you already have a current equation defined, you can use <blue shift> SOLVE and <blue shift> PLOT to go directly into the solve and plot menus. The other way, using <orange shift>, involves an extra step. The <blue shift> LAST MENU key also is useful here, particularly if the page you last used is not the first one. -- Dave Seaman ags@seaman.cc.purdue.edu