- The Strait of Messina is a narrow strait between the eastern tip of Sicily (Punta del Faro) and the western tip of Calabria (Punta Pezzo) in Southern Italy. It connects the Tyrrhenian Sea to the north with the Ionian Sea to the south, within the central Mediterranean. At its narrowest point, between Torre Faro and Villa San Giovanni, it is 3.1 km (1.9 mi) wide. At the city of Messina, it is 5.1 km (3.2 mi) wide. The strait’s maximum depth is about 250 m (820 ft).
- Pi in the Pentium: reverse-engineering the constants in its floating-point unit (righto.com)
Intel released the powerful Pentium processor in 1993, establishing a long-running brand of high-performance processors.1 The Pentium includes a floating-point unit that can rapidly compute functions such as sines, cosines, logarithms, and exponentials. But how does the Pentium compute these functions? Earlier Intel chips used binary algorithms called CORDIC, but the Pentium switched to polynomials to approximate these transcendental functions much faster. The polynomials have carefully-optimized coefficients that are stored in a special ROM inside the chip’s floating-point unit. Even though the Pentium is a complex chip with 3.1 million transistors, it is possible to see these transistors under a microscope and read out these constants. The first part of this post discusses how the floating point constant ROM is implemented in hardware. The second part explains how the Pentium uses these constants to evaluate sin, log, and other functions.