Bar (unit) mb (rather than the proper mbar) to denote the millibar. Between 1793 and 1795, the word bar was used for a unit of weight in an early version of the metric system. Atmospheric air pressure is often given in millibars, where standard atmospheric pressure at sea level is defined as 1013.25 mbar, 101.325 kPa, 1.01325 bar, which is about . Despite the millibar not being an SI unit, meteorologists and weather reporters worldwide have long measured air pressure in millibars as the values are convenient. After the advent of SI units, some meteorologists began using hectopascals (symbol hPa) which are
Pascal matrix both "L" and "U". In other words, matrices "S", "L", and "U" are unimodular, with "L" and "U" having trace "n". The elements of the symmetric Pascal matrix are the binomial coefficients, i.e. In other words, Thus the trace of "S" is given by with the first few terms given by the sequence 1, 3, 9, 29, 99, 351, 1275, … . The Pascal matrix can actually be constructed by taking the matrix exponential of a special subdiagonal or superdiagonal matrix. The example below constructs a 7-by-7 Pascal matrix, but the method works for any desired "n"×"n" Pascal matrices. (Note