eigenvaluen.

1927 Nature 23 July 117/1 Among those..trying to acquire a general acquaintance with Schrödinger's wave mechanics there must be many who find their mathematical equipment insufficient to follow his first great problem—to determine the eigenvalues and eigenfunctions for the hydrogen atom.

1930 P. A. M. Dirac Princ. Quantum Mech. iii. 35 The physical meaning of an eigenvalue is that there exists a state, namely, the eigenstate belonging to it, such that a measurement of the observable when the system is in this state will certainly give for result just this eigenvalue.

1938 R. W. Lawson tr. G. von Hevesy & F. A. Paneth Man. Radioactivity (ed. 2) viii. 93 A single-valued, finite, and continuous solution of the differential equation is found only for particular values of the parameter E which occurs in the equation, and these are the ‘proper’- or ‘eigen’-values of the differential equation.

1939 A. S. Eddington Philos. Physical Sci. 162 In mathematical language [existence is represented by] a symbol J with two eigenvalues, which are most conveniently taken to be 1, standing for existence, and 0, standing for non-existence.

1951 Rev. Mod. Physics XXIII. 1/2 The reason why we choose a as the known parameter and b as the eigen-value.

1955 W. Heisenberg in W. Pauli Niels Bohr & Devel. Physics 14 Schrödinger attempted..to resolve quantum theory into a simple classical wave theory. The motive for this attempt was the discovery that the discrete eigenvalues appeared in wave mechanics not as energies, but as the eigenfrequencies of waves.

1958 P. A. M. Dirac Princ. Quantum Mech. (ed. 4) ii. 36 The set of eigenvalues of a real dynamical variable are just the possible results of measurements of that dynamical variable and the calculation of eigenvalues is for this reason an important problem.