HP 48gII - Manual (Page 581)

Page 18-10
A plot of frequency count, f
i
, vs. class marks, xM
i
, is known as a frequency
polygon. A plot of the cumulative frequency vs. the upper boundaries is
known as a cumulative frequency ogive. You can produce scatterplots that
simulate these two plots by entering the proper data in columns 1 and 2 of a
new
ΣDAT matrix and changing the
Type
: to
SCATTER
in the PLOT SETUP
window.
Fitting data to a function y = f(x)
The program
3. Fit data..
, available as option number 3 in the STAT menu,
can be used to fit linear, logarithmic, exponential, and power functions to
data sets (x,y), stored in columns of the
ΣDAT matrix. In order for this
program to be effective, you need to have at least two columns in your ΣDAT
variable.
Example 1 – Fit a linear relationship to the data shown in the table below:
• First, enter the two rows of data into column in the variable ΣDAT by
using the matrix writer, and function STO Σ.
• To access the program
3. Fit data..
, use the following keystrokes:
‚Ù˜˜@@@OK@@@ The input form will show the current ΣDAT,
already loaded. If needed, change your set up screen to the following
parameters for a linear fitting:
x 0 1 2 3 4 5
y 0.5 2.3 3.6 6.7 7.2 11