Spacing of velocity channel not correct for negative velocities

[MatthewWhiting]

Testing with an M31 cube shows the VOPT column running into the DEC column:

----------------------------------------------------------------------------------------------------------------------------------------------------------------------
   ObjID           Name     X     Y     Z         RA       DEC   VOPT      MAJ      MIN     PA        w_50        F_int    F_peak  X1  X2  Y1  Y2  Z1  Z2    Npix Flag
                                                                [m/s] [arcmin] [arcmin]  [deg]       [m/s]     [Jy m/s] [Jy/beam]                           [pix]     
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
       1 J004259+412032 495.1 573.0  79.9 00:42:59.6 +41:20:32-300243.924   134.43    36.30  34.33 2653355.567 33563383.876     0.602 288 712 295 833   0 145 2693962    E

Perhaps not testing for negative velocities? If not, we should!

(Note that example was from a Selavy run, but it uses the Duchamp code to generate that output and size the columns...)

[MatthewWhiting]

Fixed in [1265]. The check functions were blithely taking the log of the input value, without caring whether they were positive or negative. Ensuring it logs the absolute value solves the problem.

Closing ticket.