Dec 092017

Excellent equation plotter that works with EGA. | |||
---|---|---|---|

File Name | File Size | Zip Size | Zip Type |

AGR.BAS | 38439 | 9064 | deflated |

AGR.EXE | 86784 | 38334 | deflated |

README | 7040 | 2977 | deflated |

# Download File AGR.ZIP Here

## Contents of the README file

Instructions for

A Graphing Routine

This program requires EGA and displays 2- and 3-dimensional graphs in

vivid color on a color monitor. It displays quite well on mono-

chrome, too. The original program, written in Turbo Basic, is in-

cluded for your convenience. The program is quite self-explanatory,

but we shall present a guide to its features. An 8087 mathematics

coprocessor chip is highly recommended, as this speeds graphing

considerably.

You are first asked if you want to write the functions in AOS or RPN

logic. AOS is the logic of Texas Instrument calculators and is the

way one ordinarily writes algebraic expressions. RPN is the logic of

Hewlett-Packard scientific calculators. Consult these manufacturers

if you need instructions in the logics. AOS is easier for the

programmer to write, but the graphs will run faster if the functions

are written in RPN.

You then choose whether you want to graph in 2 or 3 dimensions and

whether the graph should be written in ordinary rectangular coordi-

nates (y = f(x) or z = f(x,y)) or in parametric rectangular coordi-

nates (x = f(t), y = g(t) in 2 dimensions, or x = f(u,v), y = g(u,v),

z = h(u,v) for 3-dimensional surfaces). Curves in space are always

entered in the form x = f(t), y = g(t), z = h(t). In 2 dimensions

you have the third option of polar coordinates r = f(t), where t is

used for theta in radians.

You have the chance to correct entry errors reasonably often, since

you are frequently asked if everything is ok. Hit "n" to go back and

change the latest choices.

When you are asked to enter a function, you are told the logic you

have chosen and the functions available to you. USE LOWER CASE

VARIABLES ONLY! This program does not recognize upper case letters

at all. Note that "sqr" and "cube" square and cube the variables

they follow whereas "sqrt" and "cuberoot" take the square and cube

roots of their variables. In AOS, only the functions "sqr" and

"cube" follow their variables (so "3 sqr" yields 9); all other

operators precede their variables in AOS logic.

In RPN logic, the space is the delimiter (so "5 2 sin +" produces

5 + sin 2 = 5.909...). There is no "enter" instruction: "x" recalls

the value of x whenever it appears, and "sto1", "sto2", and "sto3"

allow you to store three (awkward) values for recall later in the

expression (so "x sqr y sqr + sto1 chs exp rcl1 /" computes

2 2

-(x + y ) 2 2

e /(x + y ),

for example).

In AOS logic the space is the delimiter, but so also are +, -, *, /,

^, (, and ) delimiters (so the displayed expression above would be

entered as "exp(-x sqr-y sqr)/(x sqr+y sqr)", with additional spaces

added as desired for clarity). Do not put spaces in the middle of a

word ("ex p" will not be read as "exp").

You are asked for minimum and maximum values of the variables. The

first values must be less than the second one and they can be sepa-

rated by either a space or a comma. Many entry errors will be caught

immediately and you will be asked to re-enter the values. You can

correct other errors by answering "n" to the "Is everything ok?"

question that always follows shortly.

After you have entered the functions and the variable limits, you are

asked "Plot every nth pixel for n =" when you are in 2-dimensional

rectangular coordinates. The screen has 640 pixels across. For most

graphs it is sufficient to plot every 2nd to every 5th pixel. The

program draws straight lines between plotted points. Thus you would

usually enter a positive integer from 1 to 10 here, but it could be

any positive number. For certain graphs with great variation, it may

be appropriate to plot even more points than the 640 screen pixels.

The smaller n is, the longer the graph takes to plot and the more

accurate it is. I usually use n = 3 for most graphs.

For polar graphs I usually use n = 20 when asked the corresponding

question. This plots 144 points. Again, n must be positive. The

next question asks where, in revolutions, you want to start and stop

plotting. For example, to let theta run from -pi/2 to +pi/2, you

would enter "-1/4, 1/4". Polar graphing also asks whether you want

coordinate circles plotted. The usual answer is "y" for yes. Then

you can estimate coordinates better.

For 3-dimensional graphs you are asked how many lines you would like

in the x- and y-directions (or in the u- and v-directions). You can

use any number from 1 to 80. Generally 5 to 40 lines give a good

graph. The number of points plotted is the product of one more than

each of the two numbers. Thus for 5 lines in the u-direction and 40

in the v-direction, the program will plot a grid of 6x41 = 246

points. The time required to do the plotting varies accordingly. If

you are graphing a space curve, you are asked "How many t-values?".

Generally 40 to 100 points suffice, although 1 to 2000 will be

accepted.

After a 3-dimensional plot is completed, you must hit any key to see

the function displayed. Two-dimensional graphs automatically display

the function when graphing is complete. To continue, hit any key

(again). You are asked "Do you want to graph this same function

again?" If you answer "y", you can re-enter the variable limits and

re-graph the last function that you just graphed. Thus you can

"zoom" any function after graphing it, without having to re-enter

the function. If you answer "n", then you are asked if you want to

graph another function on top of this one. A "y" answer allows you

choose (in most cases) whether you want to use a new color and then

to enter a new function and plot it on the same axes on top of the

previously-plotted graph(s). Another "n" answer and you are asked

to decide whether you want to quit or start over right from the

beginning. A "p" answer (plot a new graph) saves you from having to

load the program again.

The 3-dimensional rectangular graph (only) has a built-in hidden-

line routine included. Also the "underside" of the graph is a

different color from the "top" of the graph. Hence plotting another

graph on top of such a graph, although permitted, is not recommended.

Also, the colors do not change here when a new graph is plotted.

This program is supplied as shareware. You are encouraged to pass

it along to others, along with the original Turbo Basic listing and

this file. If you use this program, you are asked to mail $5 to

the author, listed below. If you wish the latest version of this

program on disk, please send $10. The first person sending any

valid correction to the program will receive a free update disk.

Send your $5 or $10 to

Clayton W. Dodge

Mathematics Department

University of Maine

Orono, Maine 04469

AGR, ver. 1.00

December 9, 2017
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