The standard deviation is a measure of how much a dataset differs from its mean; it tells us how dispersed the data are. A dataset that’s pretty much clumped around a single point would have a small standard deviation, while a dataset that’s all over the map would have a large standard deviation.
Given a sample the standard deviation is defined as the square root of the variance
Here you can find a Welford’s method for computing (single pass method) that avoids errors in some cases (if the variance is small compared to the square of the mean, and computing the difference leads catastrophic cancellation where significant leading digits are eliminated and the result has a large relative error)
User may enter up to 50 symbols from their market watch in either a long or short basket for viewing. The symbols for the chart can be changed to any symbol in the display with a click on the symbol. Statistics including ATR for the chart period, points gained or lost from a weeks start and position gains or losses and lots exposure are displayed. The statistics week may be changed with simple clicks on the display, and the display may be dragged and dropped to different locations. The load on quote processing is kept low by simply posting an event that starts the processing for a display update.Hull moving average
Hull moving average (non-repainting version)