Logarithmic Regression
The logarithmic regression option finds the equation of a logarithmic equation of
the form y = a + b ln x that best fits a set of data.
First, press 
to
enter the data .
Press 
to view the statistics calculation options.
The values of x must be greater than zero. (This is because the method for determining
the values of a and b in the regression equation is a least-squares fit on the
values for ln x and y.)
Press .
Enter the columns to be used for the x and y entries, c1 and c2 in this case.
The regression equation can be automatically stored in the equation editor by selecting
the Stor RegEQ
Therefore, the best-fit logarithmic equation for this data is approximately
y = 2.84 + 3.06 ln x.