The holmium laser, which operates in a wavelength of 2.1 microns, is highly absorbed by water and has a shallow penetration depth of approximately 0.4 mm. As a pulsed mode laser, the Holmium reduces deeper thermal effects and charring which are more prevalent in Continues Wave lasers (e.g. Thulium, KTP).
In statistical theory, covariance is a measure of how much two random variables change together. In other words, covariance is a measure of the strength of the correlation between two random variables. Also, it can be considered as a generalization of the concept of variance of two random variables.
Knowing the covariance of stocks helps you build a better portfolio. The covariance of two variables tells you how likely they are to increase or decrease simultaneously. A high, positive covariance between two stocks means that when the price of one goes up, that of the other usually does too.A high negative figure means that when one stock advances, the other generally retreats.inding the Covariance. Now you will have two sets of data: the daily deviation of Stock A from the average price of Stock A; and the daily variation of Stock B from its average price. For each day in your data set, multiply the deviation of Stock A by the deviation of Stock B.