The Unsorted BBS Collection/thegreatunsorted.tar/thegreatunsorted/misc/graphit3.hlp

Text File | 1990-08-22 | 6KB | 93 lines

                             THE DEFAULT SETTINGS

           When you run GraphIt! without any command-line arguments,
                     the following settings are in effect:
       Start of range:  (-12.0, -8.14*)   End of range:  (19.5, 8.14*)
             Fineness:  1.0 **               Step rate:  0.0625  (1/16)
              Legends:  ON                    Warnings:  OFF
              Printer:  OFF                 AutoRedraw:  ON

This provides a basic rectangular grid of decent size with the origin
centered, a square aspect ratio (a 1x1 square on the grid really LOOKS
square), and a good resolution graph.

 * on VGA + or - 8.48 because its 30 text rows allow more of the vertical
   pixels to be used for the graph than the 25 rows of CGA/EGA.
** 0.5 on CGA systems to speed up graphs with reduced resolution.
──────────────────────────────────────────────────────────────────────────────
                             VIEWING THE SETTINGS

    The  current settings are almost always displayed whenever you change  one
of them. Every item under Options (unless aborted)  will bring up the settings
screen.   You  can  also look at them manually by selecting  Settings  in  the
Options menu.                                    Press PgDn for help on Scale.
                              CHANGING THE SCALE

    The  scale function allows you to change the scale of the graph  you  have
on-screen  while  keeping the center of  the display the same (the  origin may
move but if (2,2)  is at the middle of the  screen,  it will stay there).  The
scale  is  totally relative to the size of the  grid that is presently  on the
screen,   so you need not make any comparison with an  absolute scale of 1. To
rescale the grid,  select "Scale"  from the options menu.  Then respond to the
prompt according to the following guidelines:

    Enter a positive number to zoom in,  or a negative number to pan out.  The
number of units across the screen will be divided or multiplied by that number
accordingly.  Numbers between -1  and 1,  inclusive,  are invalid because they
produce meaningless values.  Decimals greater than 1 or less than -1 are valid
though.

    If  you  enter  an invalid number,  you will be asked again to  enter  the
scale. To abort rescaling, just press enter on a blank line.

    To scale the default range,  use the "/S" option on  the command line (see
Appendix A of GRAPHIT.DOC).

                                                 Press PgDn for help on Range.
                              ADJUSTING THE RANGE

    The ability to adjust the grid by  inputting the beginning and end of  the
desired  range  is  one of the most powerful and  flexible  features  GraphIt!
offers. It can rescale the grid  to either  be a perfect fit for  the function
you are graphing so that as much of it is visible as possible or to render the
most accurate image possible on even the lowest resolution CGA screen. Both of
these features can be accomplished by selecting Range in the Options menu.
    To  create  a grid such as the first,  graph an equation on  the  standard
grid,  and from that graph determine the top-,  bottom-,  left-  and rightmost
extremities  of the graph,  and respond with the proper values to the 4  Range
prompts.  The new grid may be somewhat expanded or compressed depending on the
aspect  ratio,   but  it will show the same amount of graph  in  much  greater
detail.
    To create a more accurate representation like the second grid,  have  some
idea in your mind as to the left,  right,  and top of the grid.  Enter these 3
numbers in the first 3 range prompts,  and on the fourth one just press enter.
Voilà.   The bottom of the grid will be AutoScaled to the exact y to  x  ratio
needed  to  get a square aspect ratio...if it isn't,  you'd better  check  the
vertical  size knob on your monitor!  To set the range from the command  line,
use the /X1:, /X2:, /Y1:, /Y2:, and /Y2 options [described in Appendix A].

                                              Press PgDn for help on Fineness.
                            ADJUSTING THE FINENESS
    The  fineness factor determines how high the resolution of the graph  will
be, and in effect, also the amount of time it takes to complete the graph. The
default fineness factor of 1 is quite adequate in most circumstances. With the
addition  of SmartFineness automatic fineness adjustment in the  graph-drawing
loop, the manual fineness adjustment has become almost obsolete, but I left it
in to accomodate the need for especially sharp graphs or for especially  quick
renderings.  SmartFineness automatically decreases the fineness when the point
being  graphed  is not on the  screen to speed up blank areas,  then  recovers
automatically  and  backtracks  to the spot where the  graph  comes  on-screen
again.  It also  varies the fineness with  the  slope of  the  equation  being
graphed,  so steep graphs are  tracked more effectively.  As the  fineness  is
increased,  more  of the curve will be smoothed out,  but remember that if you
increase the fineness factor to 5, the computer will be slowed down to 1/5 its
normal graphing speed under the load of all the extra calculations.
    If you have CGA adapter,  GraphIt! assumes you are using an 8088 non-turbo
PC  and reduces the fineness to 0.5  to speed up graphing;  the difference  in
resolution  is  usually  not  very  noticeable on the  CGA  screen,   but  the
difference in speed is.
    To change the fineness factor, select Fineness from the Options menu.  Any
value  greater than zero is valid;  however I would recommend not going  below
0.25, as the image quality suffers.
───────────────End of Options help. Press ESC to return to menu.──────────────