(C) Andre Ratel (1998)
Why I wrote ARLine
When I was a college student (in the old days of the slide rule), I
just hate having to write those lab reports, especially when there
were graphs involved. Putting all the experimental dots on millimeter
paper and drawing the uncertainty rectangles around each of them was
so boring that my mind tended to wander. And when, back to reality, I
thought the job was almost finished, I then realized that I had made
some stupid mistake and that I needed to start all over again. By the
end of the semester, I was so fed up that I just put the points on the
graph and did not bother at all with the uncertainties. This resulted
in bad marks but, at least, I had then a little more time to really
understand the theory.
Years later, I found myself teaching Physics in college. My students,
then, had pocket calculators but, to my taste, they were still putting
too much time on lab reports. Too often, they had to redraw their
graphs because of bad scaling or some other dumb mistake. I would have
preferred that they spent a little less time on these repetitive tasks
and a lot more in studying subjects they did not understood very well
like Newton’s third law and the conservation of momentum.
ARLine should help alleviate this problem. It was written
especially with the science student in mind.
What is ARLine?
Let us say that, from a lab experiment, you obtained a set of N
data points with their uncertainty bars. You suspect a linear dependency
of the y-values on the x-values, that is y can be
y = A x + B
with A and B constants.
ARLine will then allow you
Moreover, ARLine will automatically calculate
- to enter in a table the experimental values and their
uncertainties and, later on, to save or print this table
- to display on a graph these experimental points and their
uncertainties (using up to 6 distinct symbols) and, later on,
to save, print, or paste this graph in another application
- to enter theoretical values for the slope A and
intercept B and to display the theoretical line on
Slope and intercept values can be displayed on screen, saved to file, or
printed. You can also choose which of these lines will be drawn on the
- the line of least squares
- the lines of minimum and maximum slopes passing through all
the uncertainty bars or, if not possible, passing through the
largest number of uncertainty bars
- the line of mean slope obtained from the lines of minimum and
maximum slopes by averaging their slopes and averaging their
- the lines of minimum and maximum intercepts passing through
all the uncertainty bars or, if not possible, passing through
the largest number of uncertainty bars
- the line of mean intercept obtained from the lines of minimum
and maximum intercepts by averaging their slopes and averaging
- the mean line whose slope is obtained from the mean slope line
and whose intercept is obtained from the mean intercept line.
Working with ARLine
ARLine consists of four main windows:
- the Data Window where we input the table of experimental values
- the Settings Window where we define how the graph will appear
and what we want to see on it
- the Graph Window where the graph will be drawn and where we will
be able to save it, print it, or copy it to the clipboard
- the Results Window on which are displayed the slope and intercept
values calculated from the data.
You need also
- MS Windows 95 or later versions
- a screen resolution of 1024*768 pixels or better
- about 873 kB of disk space for the executable and 500 kB for
some sample files and for the manual (in pdf format).
And be reassured: installing ARLine or your system involves
no dumping of files in your Windows directory and no messing with
the win.ini file or the Registry.
- Acrobat Reader in order to be able to read the manual.
You can get the current version of
Acrobat Reader free from the
This new version of ARLine will not work on a system configured
for the decimal comma. You will need to use the decimal point for your
input (for example 2.54 instead of 2,54).
ARLine is fully functional (not crippleware) and there
is no time limit on its functionality.
It is free unless you make some money with it. If this is the
case, it is only fair that I get part of it and you need to
contact me (at
so that we can come to an arrangement.
ARLine cannot be sold (alone or bundled in a package) without
my written permission.
The ARLine package contains the following files:
- ARLine.exe: this is the executable
- Samples\*.dat files: those contain data for the
- Samples\*.stg files: those contain graph
configurations for the examples
- ReadMe.txt: a text file (in ASCII format) containing
last minute information
- ARLine.pdf: this is the manual (in pdf format).
You can download the package ARLine.zip
If you have an old version of ARLine and you want to know
what is new in this one, you can have a look at the
History.txt file before downloading the