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1994-07-11
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Help file for !SciFunc
© Andrew Ayre 1994
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!SciFunc supports Acorn's !Help application.
Introduction...
In the Public Domain is a suite of programs called SciApps, which allow
you to produce scientific graphs. Each graph can have a model fitted to it,
so things like lines of best fit can be calculated. SciFunc complements
those applications.
The coordinates for the points on a graph are entered using the SciEdit
application one by one, then saved in a SciGraph file.
This is fine if you are entering the results of experiments, but if you
want to draw the graph of Y=X² or Y=ln |4.5X³-3.1X²+0.75X| then you have to
manually calculate the y value for each value of x.
SciFunc does this for you. You simple enter the function and a few other
details, and a SciGraph file is produced for you, ready to be used by the
other programs in the SciApps suite.
Please note: this application is not much use without the SciApps suite
of programs.
SciFunc contains a standard list of functions which are built into BASIC
V, eg. ABS(), EXP(), LN(), RND(). You can also define your own thus
simplifying the amount that needs to be entered into the program.
Using...
Once loaded click on the icon to bring up the main window. Enter the
function into to the writeable icon (theres no need to enter the 'Y=' bit).
Specify the range of x values that will be calculated by entering the
minimum and maximum values of x into the next two writeable icons.
In the last writeable icon, enter the size of the step (the amount that x
will be increased by each time a calculation has been done).
Press Return or click on Calculate. If you have used SIN, COS or TAN in
the function, then you will be asked if you want to use Radians or Degrees.
Once you have clicked on the relevent radio icon, click on OK.
A standard save box will now appear. Drag the icon to a filer window. If
all is well, the file will be saved, ready to be used by !SciGraph and
!SciModel.
If you have used LN or LOG in the function and the minimum value for x is
zero or less, then the function might be uncalculatable. The saving will be
aborted.
Clicking on 'Clear' in the main window will empty the writable icons.
To aid you in entering functions, SciFunc has a menu containing a list of
standard functions. This is obtainable by clicking (with SELECT) on the
little menu icon to the right of the writeable icon where the function goes.
All the functions are standard ones that are built into BASIC V. You can
remove individual ones or change the order of them by editing the
'Functions' text file inside the application directory. You can also define
your own custom functions. Two examples ( called FULLRECT(X) and BIGGER(X) )
are at the bottom of the menu, and when used will make all the negative
parts of a sine graph positive (full wave rectification). Custom functions
must be left exactly as shown in the menu, but can be put inside other
built-in functions. eg:
FULLRECT(2X) - won't work
INT(FULLRECT(X)) - will work
The functions file...
This file contains all the functions that appear on the menu. You can edit
this to suit yourself, but there are a few things to be noted:
(1) Comments must start with a '*', and must come at the start of the file
only.
(2) The standard functions must come immediately after the comments and
before the custom functions.
(3) Lines that define custom functions must start with a '>' and come at the
end of the file. The equals sign must have a space either side of it, with
the text to appear on the menu on the left, and the definition of the actual
function on the right. There must be no spaces between the > and the name of
the function. As demonstrated by the BIGGER(X) function, the definitions can
contain other custom functions.
(4) Don't forget to make sure that the file ends with a Return.
Some more things to be noted:
Example: say you wanted to enter the function Y = 4X². You can't just
enter it like that because BASIC won't like it. Instead you have to enter it
like: Y = 4*(X^2). Don't forget to put the brackets in the right place, Y =
(4*X)^2 is not the same thing.
You can use PI in the function, but not in the min, max and step fields.
For those you will have to enter something like 3.1415927.
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This software may be freely copied as long as none of the files are altered
or tampered with, and no profit is made.
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