gtf - calculate VESA GTF mode lines
gtf h-resolution v-resolution refresh
  [-v|--verbose] [-f|--fbmode]
  [-x|--xorgmode]
Gtf is a utility for calculating VESA GTF modes. Given the desired
  horizontal and vertical resolutions and refresh rate (in Hz), the parameters
  for a matching VESA GTF mode are printed out. Two output formats are
  supported: mode lines suitable for the Xorg xorg.conf(5) file, and mode
  parameters suitable for the Linux fbset(8) utility.
  - -v|--verbose
- Enable verbose printouts This shows a trace for each step of the
      computation.
- -x|--xorgmode
- Print the mode parameters as Xorg-style mode lines. This is the default
      format.
- -f|--fbset
- Print the mode parameters in a format suitable for fbset(8).
Andy Ritger.This program is based on the Generalized Timing Formula (GTF(TM))
    Standard Version: 1.0, Revision: 1.0. The GTF Excel(TM) spreadsheet, a
    sample (and the definitive) implementation of the GTF Timing Standard is
    available at <ftp://ftp.vesa.org/pub/GTF/VTF_V1R1.xls>.