The concept of thinking of how a filter works in the frequency domain as well as how it works in the time domain is central to the understanding of the indicators that will be developed. Low frequencies near zero are passed from input to output with little or no attenuation. Since higher frequencies are blocked from being passed to the output, the SMA is a type of low-pass filter—passing low frequencies and blocking higher frequencies.
■ Nonrecursive Filters
This is a technical resource book written for self-directed traders who want to understand the scientific underpinnings of the filters and indicators they use in their trading decisions rather than to use the trading tools on blind faith. CyCycle Analytics for Traders will allow traders to think of their indicators and trading strategies in the frequency domain as well as their motions in the time domain. The descriptions are written for understanding at several different levels. Traders with little mathematical background will be able to assess general market conditions to their advantage. More technically advanced traders will be able to create indicators and strategies that automatically adapt to measured market conditions by using combinations of computer code that are described.
We can see the frequency characteristic of the transfer response by starting with a five-element SMA and then generalizing. John F. Ehlers worked as an electrical engineer at one of the largest aerospace companies in the industry before retiring as a senior engineering fellow. A graduate of the University of Missouri, he has been a private trader since 1976, specializing in technical analysis. The discoverer of Maximum Entropy Spectrum Analysis, he writes extensively on technical trading and speaks internationally on the subject. A “file MD5” is a hash that gets computed from the file contents, and is reasonably unique based on that content. All shadow libraries that we have indexed on here primarily use MD5s to identify files.
Book preview
Equation 1-7 shows that the zero in the transfer response occurs exactly at the Nyquist frequency. We have succeeded in completely canceling out the highest possible frequency in the four-bar SMA. In this case, the roots of the polynomial are called the poles of the transfer response because a zero in the denominator of the transfer response causes the transfer response to go to infinity at that point. One can visualize the transfer response as the canvas of a circus tent in the context of complex numbers, and the poles in the transfer response are analogous to the tent poles. While it is possible to choose coefficients that cause the transfer function to blow up, frequencies are constrained to be real numbers, and therefore it is relatively easy to avoid the complex pole locations. In this case, the higher frequencies are passed, and the lower frequencies are severely attenuated by the filter.
Profits in the Stock Market
In addition, you will find that the responses in the time domain and in the frequency domain are intimately connected. When designing filters for trading, it is beneficial to consider the response in both of these domains. It is important to remember that no filter is predictive—filter responses are computed on the basis of historical data samples. It is most convenient to consider filters as stonewall filters that have only a pass band and a stop band with the boundary between them located at a critical cycle period.
📂 File quality
The vertical axis is the amplitude of the output relative to the amplitude of the input data in decibels. Figure 1.1 shows that there are zeros in the filter transfer response in the frequency domain as well as in the time domain. Cycles are a unique kind of trading analytics, being one of the few types of market data that can be accurately measured. But understanding what the cycles mean and which trades to make based on them is an extremely complex process. Cycle Analytics for Traders is a technical resource for self-directed traders that explains the scientific underpinnings of the filters and indicators used to make effective and profitable trading decisions.
- Cycle Analytics for Traders will allow traders to think of their indicators and trading strategies in the frequency domain as well as their motions in the time domain.
- John F. Ehlers worked as an electrical engineer at one of the largest aerospace companies in the industry before retiring as a senior engineering fellow.
- Cycles are unique because they are one of the few characteristics of market data that can be scientifically measured.
- But understanding what the cycles mean and which trades to make based on them is an extremely complex process.
The interesting thing about this equation is that we have now written the transfer response as a generalized algebraic polynomial. Input data are supplied to the system, and the system provides the resultant as an output. However, the system between the input and output can be as complex as desired.
- Band-stop filters would reject only cycle components also centered at the critical cycle period.
- However, the cyclic swings can be helpful to know when to buy on a dip in the direction of the trend.
- In the most general sense, there is a triple infinity of parameters–period, phase, and amplitude–that must be identified simultaneously to completely describe the cycles.
This is really bad for filters used in trading because using more data means the filter necessarily has more lag. Minimizing lag in trading filters is almost more important than the smoothing that is realized by using the filter. Therefore, filters used for trading best use a relatively small amount of input data and should be not be complex. In this chapter you will find the difference between nonrecursive filters and recursive filters, and combinations of the two, enabling you to select the best filter for each application.
The output divided by the input is the transfer response of the system. It is this transfer response that describes the action of the system. The concepts are presented so they can be understood with only a background in algebra. The writing style in the book is intentionally terse so the reader doesn’t need to wade through a mountain of words to find the ideas being presented.
This is a technical resource book written for self-directed traders who want to understand the scientific underpinnings of the filters and indicators they use in their trading decisions. There is plenty of theory and years of research behind the unique solutions provided in this book, but the emphasis is on simplicity rather than mathematical purity. In particular, the solutions use a pragmatic approach to attain effective trading results. Cycle Analytics for Traders will allow traders to think of their indicators and trading strategies in the frequency domain as well as their motions in the time domain. This new viewpoint will enable them to select the most efficient filter lengths for the job at hand.
Band-pass filters would pass only cycle components centered at the critical cycle period. Band-stop filters would reject only cycle components also centered at the critical cycle analytics for traders cycle period. If that is the only term used in the filter, the filter is said to be nonrecursive.
Since trends can be viewed as pieces of a very long cycle, a high-pass filter is basically a detrender because the low-trend frequencies are rejected in its transfer response. Equation 1-12 is exactly the equation for an exponential moving average (EMA). Note that the sum of all of the coefficients on the right-hand side of Equation 1-11 sum to 1 so that the filter has no noise gain. By thinking in terms of the transfer responses, you will easily make the transition between filter theory and programming the filters in your trading platform. Cycle Analytics for Traders shows traders how to approach trading as a statistical process that should be judged from the long-term view, rather than a small sample set of just a few trades—no matter how profitable those few are. With this practical and informative book as a guide, any trader can master cycle analytics, letting statistics and science light the way to long-term trading success.
