Magnetic fields from straight filaments, rectangular sheets, and rectangular bars

The derivation and the use of three Fortran programs are described: FIFL = Field from a straight filament of finite length. FIRS = Field from a rectangular sheet of infinitesimal thickness. FIRB = Field from a rectangular bar of finite length. The three geometries in question might suggest a logical extension of the solution for the simplest geometry, i.e., the linear filament, into the successively more complicated cases, i.e., the rectangular sheet and the rectangular bar. The programs to be discussed were; however, developed independently. Each program is, therefore, the result of a different mathematical approach and is discussed. (auth)