Python allows free creation of plots, unlike expensive, stagnant graphing calculators. Import NumPy and Matplotlib for basic ...

As the name implies, the derivimeter finds the derivative of a function. To do that ... the angle and find the true derivative using a table of tangents. [Chris] has another derivimeter from ...

Just over twelve months later, with the parts all spread out on a table, it quietly spat out ... By 1976, a four-function calculator cost only a few dollars. In 1972, 5 million calculators were ...