Version v2.58d (September 2021)

Include a switch to take the absolute value of line wavelengths. In the database, lines with theoretical wavelengths are given negative wavelengths. These were not included in the synthetic spectrum calculation in previous versions. With the switch, called llinabs, set in the main xstar subroutine, this can be controlled. If llinabs=1 then the lines with negative wavelengths are included in the synthetic spectrum.