Nexius<br />Yes, some of us do use this in our everyday lives. Imaginary numbers (using the square root of -1) allow us an additional dimension to describe certain phenomena. Describing the voltage and current in three phase power distribution systems comes to mind. Differential calculus allows us to model rates of change, integral calculus provides insights on accumulated amounts. Tensor calculus models all of this in three dimensions, plus rates of rotation, plus rates of change of rotation, plus divergence, plus rates of change of divergence. A type of math called symmetrical components (discovered in 1918) (combining some discussed above) can model the transients occurring in a power line after a lightning strike. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>