Pressure measurement because atmospheric pressure is always changing and the reference in this case is fixed at 1 bar. To produce an absolute pressure sensor, the manufacturer seals a high vacuum behind the sensing diaphragm. If the process-pressure connection of an absolute-pressure transmitter is open to the air, it will read the actual barometric pressure. The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m or kg·m·s). This special name for the unit was added in 1971; before that, pressure in SI was expressed in units such as N·m. When indicated, the zero reference is
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