Write MATLAB Skeleton code:

Variations in lung volume during breathing cause variations in heart rate, an effect known as respiratory sinus arrhythmia. The file rsa .mat contains two sig- nals measured from a human subject: instantaneous lung volume and heart rate at three different frequencies of breathing. Use the grid search method to fit a sine wave to each signal and determine the frequency response of heart rate to lung vol- ume at each frequency. Does the frequency response change with frequency?