## DESCRIPTION

A rhumbline (loxodrome) is a line following a constant angle of the compass (i.e., a line of constant direction). It crosses all meridians at the same angle, i.e. a path of constant bearing. d.rhumbline displays the rhumbline joining any two user-specified points in the active frame on the user's graphics monitor. The named coordinate locations must fall within the boundaries of the user's current geographic region.

The user has to specify the starting and ending longitude/latitude coordinates of the rhumbline and (optionally) the color in which the rhumbline will be displayed; in this case, the program will run non-interactively.

## EXAMPLE

A geodesic line if shown over the political map of the world (demolocation dataset):

    g.region vector=country_boundaries -p
    d.mon wx0
    d.vect country_boundaries type=area
    d.rhumbline coordinates=55:58W,33:18S,26:43E,60:37N \
      line_color=yellow
    # show additionally 10 degree grid
    d.grid 10

Rhumbline (loxodrome)

## NOTES

This program works only in GRASS locations with longitude/latitude coordinate system.

## SEE ALSO

d.geodesic, d.grid, m.measure

## AUTHOR

Michael Shapiro, U.S. Army Construction Engineering Research Laboratory