- Derivative (Wikipedia)
In mathematics, the derivative shows the sensitivity of change of a function’s output with respect to the input. Derivatives are a fundamental tool of calculus. For example, the derivative of the position of a moving object with respect to time is the object’s velocity: this measures how quickly the position of the object changes when time advances.
- Middle Fork Snoqualmie River (Wikipedia)
The Middle Fork, approximately 41 miles (66 km) long, originates from Chain Lakes, 47°33′30″N 121°14′15″W, and flows south to Williams Lake, then in a westerly direction until it meets with the North Fork near North Bend. It receives the waters of the Taylor River and the Pratt River in short order about halfway between its source and its mouth. It has one major waterfall along its course. The upper reaches of the Middle Fork, Taylor, and Pratt river valleys are within the boundaries of the Alpine Lakes Wilderness area.
