Tham khảo tài liệu 'the profit magic of stock timing the markets_7', tài chính - ngân hàng, đầu tư chứng khoán phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 184 Spectral Analysis-How to Do It and What It Means FIT YOUR DATA WITH A STRAIGHT LINE The equation of any straight line is of the form P A B 0 P is the variable you would plot vertically on a graph and 7 is the variable you would plot horizontally. A and B are constants for a given line. In fact when known these describe a particular straight line as uniquely as the quantities period amplitude and phase describe a particular sine wave. Your present problem is to find values of 1 and 5 for a straight line which comes as close as possible to fitting all of the points on your frequency vs. time plot. For consistency we can rewrite the line equation using the symbols assigned to frequency and time earlier in the chapter co A B t As rewritten w is the angular frequency you are measuring. Remember that you can measure period from the filter output then convert this to angular frequency. The quantity t now represents time from any arbitrary time zero usually taken at the start of your data . To start arrange your data in two vertical columns one for the measured frequencies and the other for the times associated with them as measured from the chosen time zero. It is a good idea right here to make your time units compatible . if you use radians per year to describe frequency use fractions of years to describe time etc. Now looking across the tabulation the data appears in pairs an angular frequency associated with a time in each case. Count the number of such pairs and label the result as N. You must now do the following things with this data and jot down the results 1. Add up all the w s and label the result C. 2. Add up all the t s and label the result D. 3. Square all the t s multiply each one by itself and add up these values. Label the sum E. 4. Multiply each co by the associated t and add up all the products. Label the result F. 5. Square the sum of all the fs found in Step 2. Label the result G. You have now written down six numbers N the number of pairs of .
