The use of the pseudo-Voigt function in the variance method of X-ray line-broadening analysis. Erratum

In the paper by Sánchez-Bajo & Cumbrera [J. Appl. Cryst. (1997), 30, 427–430], there was an error in equation (11): the letter k appeared in the place of η. The correct equation (11) is as follows: W(σ) = β⁻¹[−2ηw³ arctan(σ/w) + 2ηw²σ + 2( 1 − η)F(σ)]. (11)