Pewter of the Bronze Age in the Near East. The earliest piece of pewter found is from an Egyptian tomb from 1450 BC. The constituents of pewter were first controlled in the 12th century by town guilds in France. By the 15th century, the Worshipful Company of Pewterers controlled pewter constituents in England. This company originally had two grades of pewter, but in the 16th century a third grade was added. The first type, known as "fine metal", was used for tableware. It consisted of tin with as much copper as it could absorb, which is about 1%. The second type,
Pivot element Pivot element The pivot or pivot element is the element of a matrix, or an array, which is selected first by an algorithm (e.g. Gaussian elimination, simplex algorithm, etc.), to do certain calculations. In the case of matrix algorithms, a pivot entry is usually required to be at least distinct from zero, and often distant from it; in this case finding this element is called pivoting. Pivoting may be followed by an interchange of rows or columns to bring the pivot to a fixed position and allow the algorithm to proceed successfully, and possibly to reduce round-off error. It is