Example: Growth of Organisms

Click here to open an associated Mathcad worksheet:

This first example shows some basic regression functions, which are used to fit equations to data. The following functions are introduced:

• line for fitting linear functions.
  
  
• pwrfit for fitting power functions.
  
  
• expfit for fitting exponential functions.
  
  
• logfit for fitting logarithmic functions.
  
  
• lgsfit for fitting logistic functions.
  
  
• sinfit for fitting trigonometric functions.

In each of the examples on the worksheet, you will be given a data set on the growth of a particular biological organism. You will then have the opportunity to vary the parameters in a fitting function. Finally, you will be able to compare your best fit "by eye" with the fit that Mathcad finds using the method of least squares.

Don't worry if you don't understand all of the details behind Mathcad's calculations here. Look at the general set-up. Try to understand how parameters affect members of a particular family of functions. You'll become better acquainted with these regression functions as you use them in subsequent examples.

For more information on mathematical biology, explore the pages of the Society for Mathematical Biology.