2008
       BL4430 - Biological Simulation Techniques: Notes on Chapter 3

The exercises in Chapter 3 require the use of some techniques of fitting non-
linear data to equations.  If you are familiar with software that can be used
for such tasks (Systat or SigmaPlot, for example), you should feel free to use
it to perform the required curve fitting.  If you do not want to use other
software, three Just BASIC programs (curfit05.bas, nonlft05.bas, and
polyft05.bas) are available for your use in the class.  They were among the
files that you downloaded from the R:\ drive at the beginning of the semester.

Use of any of these programs requires a data file.  The data files required by
all three programs have the same format.  For simplicity, be sure to put the
data file in the same folder/directory as the program file.

The data file must be a simple text file.  It is probably easiest to write the
data file using the Notepad program in Windows.  However, you can create the
data file with any software you like, as long as you save it as a text file.

The first line of the data file should be the number of X-Y data pairs you want
the program to consider.  The maximum number of pairs that the programs can
handle is 50.  (The program can be easily rewritten to handle more than that
number, if needed; however, it is not necessary for any of the exercises.)  The
minimum number of X-Y pairs is determined by statistical considerations.

The second line and following lines should show individual X-Y pairs, separated
by a comma. (It is possible to put all the data in a single line separating the
numbers by commas, but that arrangement can make it more difficult to find and
correct errors in the data.)  After you have created the text file, save it in
the same folder (=directory) as your curve-fitting programs.

To start any of these programs, load them into Just BASIC.  Change the file name
near the beginning of the program to the name of your data file.  Then RUN the
program.

For all exercises from Chapter 3 you will need to submit output from the CURFIT
program.  You can print the necessary pages with the usual technique of selecting
"print" from the menu bar of the appropriate window.  (See samples below of the
four needed outputs, which use the TRIALFIT data.)

To be acceptable, your final CURFIT F-value should exceed the value listed below.
This will indicate that you have selected an appropriate equation and, if
necessary, have chosen a suitable constant for that equation.  If your F-value
is less than the listed value, then try again using a different equation or
different constant.


3-1:  60,000     3-9:  2,000        3-12:    80      3-16:     7
3-2: 600,000     3-10:   500        3-13:   200      3-17:   250
3-3: 160,000     3-11:   315        3-14: 1,000      3-18:    20
3-4:  10,000                        3-15: 2,000

For Exercises 3-1 thru 3-4 using CURFIT, four output pages are needed for each
exercise.

For Exercises 3-5 thru 3-8 using CURNLFIT, only three pages are needed; there is
no summary page.

For Exercises 3-9 thru 3-18: use CURFIT and submit four output pages.  IN ADDITION:
  (A) If no equation from CURFIT fits the data well, then also submit four pages
      from the POLYFIT program.
  (B) If the fit for the CURFIT equation appears to be good, then you should also
      submit three output pages from the CURNLFIT program, as indicated in the
      textbook.

Required output pages from CURFIT (Figures are links to enlarged images)