The polar vortex is making a return to the forecast, but the counterintuitive weather feature is nothing to fear.

Differential equations are fundamental tools in physics: they are used to describe phenomena ranging from fluid dynamics to general relativity. But when these equations become stiff (i.e. they involve ...

E xcel has this useful feature that probably most people completely overlook—the Quick Analysis menu. If you've been manually creating charts, writing formulas for totals, or sp ...