define display # $1 = panel number; $2 = data file; $3 = Fit type. color 1 # Reset color index. panel 1 -3 -$1 # Set the selected panel. data $2 # Open the data file. xcolumn 2 ycolumn 3 ecolumn 4 ylabel \fr $3 Fitting end viewport 0.2 0.8 0.2 0.8 # Set the viewport scale. font 2 # Choose a nice font. expand 1.2 # Choose a nice expansion. display 1 gauss.dat Gaussian # Read data containing two gaussians. limits # Autoscale the limits. connect # Draw the data. box bcst bncstv # Draw the box (no X numbers). fit gauss 2 4.5 2.2 2.8 2.5 4.9 2.8 # Fit 2 gaussians. lstyle 4 # Select a dashed line style. color 3 # Set color to green. plotfit x1 x2 0.5 # Plot the fit at high resolution. color 4 # Set color to blue. plotfit x1 x2 2.0 # Plot the fit at coarse resolution. lstyle 1 # Reset line style to solid. range 6 10 # Limit the range in the X direction. fit gauss 2 4.5 2.2 2.8 2.5 4.9 2.8 # Fit 2 gaussians. range 0 0 # Reset the range to the full X-axis. color 2 # Set color to red. plotfit 6 10 # Plot the fit for the limited range. display 2 line.dat Linear # Read data scattered linearly. limits x1 x2 0 0 # Retain X limits; autoscale Y limits. symbol 2 # Select the '+' symbol. points # Display data as points. box bcst bncstv # Draw the box (no X numbers). fit lsqfit # Fit via Least Squares method. color 3 # Set color to green. plotfit # Plot the lsqfit solution. move 0 6.5 # Draw a line for... draw 1 6.5 # ... the fit legend. label \fr lsqfit (Least Absolute Deviations) fit medfit # Fit via Least Absolute Deviations. color 4 # Set color to blue. lstyle 4 # Select a dashed line style. plotfit # Plot the medfit solution. move 0 6.2 # Draw a line for... draw 1 6.2 # ... the fit legend. label \fr medfit (Least Squares Method) lstyle 1 # Reset line style to solid. color 1 # Reset color index. display 3 poly.dat Polynomial # Read data containing a polynomial. limits x1 x2 0 10 # Retain X limits; autoscale Y limits. connect # Draw the data. box bcnst bncstv # Draw the box (with X numbers). fit polynomial 5 # Fit a simple polynomial of order 4. color 3 # Set color to green. plotfit # Plot the polynomial solution. move 0 8 # Draw a line for... draw 1 8 # ... the fit legend. label \fr Polynomial fit legendre 5 # Fit a Legendre polynomial of order 4. color 4 # Set color to blue. lstyle 4 # Select a dashed line style. plotfit # Plot the Legendre solution. move 0 7 # Draw a line for... draw 1 7 # ... the fit legend. label \fr Legendre Polynomial lstyle 1 # Reset line style to solid. color 1 # Reset color index.
Figure E.9: A plot showing different ways to fit data.