Double concerto for violin, cello, and piano, Beethoven's Triple Concerto for Violin, Cello, Piano and Orchestra being perhaps the most notable, but there have been many; see the list of triple concertos for violin, cello, and piano. A notable quadruple concerto is Olivier Messiaen's incomplete "Concert à quatre". Double concerto A double concerto (Italian: "Doppio concerto"; German: "Doppelkonzert") refers to two distinct variations on the concerto. Most often, it refers to a concerto featuring two performers, as opposed to the usual single performer, in the solo role. These two performers' instruments may be of the same type, as in Bach's, Concerto for
Quadruple-precision floating-point format the double-double technique above, although that technique does not implement IEEE quadruple precision), since direct hardware support for quadruple precision is, as of 2016, less common (see "Hardware support" below). One can use general arbitrary-precision arithmetic libraries to obtain quadruple (or higher) precision, but specialized quadruple-precision implementations may achieve higher performance. A separate question is the extent to which quadruple-precision types are directly incorporated into computer programming languages. Quadruple precision is specified in Fortran by the codice_2 (module codice_3 from Fortran 2008 must be used, the constant codice_4 is equal to 16 on most processors), or as codice_5, or in