shiftvel.pro

NRAO GBTIDL
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shiftvel.pro

Last modification date:: Thu Jun 2 23:56:08 2005

shiftvel

function shiftvel(vel, voffset, [veldef=string])

Shift a velocity using a velocity offset. Note that because of the nature of the non-true velocity definitions, this is not a simply reversable shift for anything by a TRUE velocity. Namely, v=shiftvel(shiftvel(v,voffset),-voffset) will not result in the same value of v as you started out with for anything except veldef='TRUE'. If you want to undo a velocity shift using the same voffset, use unshiftvel.

Returns: the shifted velocities in m/s.
Version: $Id: shiftvel.pro,v 1.2 2005/04/08 20:36:06 bgarwood Exp $

Parameters

vel
in, required
double The velocities, in m/s, to shift.

voffset
in, required
double The velocity offset (m/s) to add to the velocities (resulting velocities are then appropriate for a frame moving at voffset relative to the original frame of vel).

Keywords

veldef
in, optional
string (def. 'RADIO') The velocity definition from one of RADIO, OPTICAL or TRUE.

Produced by IDLdoc 1.6 on Thu Jun 2 23:56:57 2005

Parameters
vel in, required double	The velocities, in m/s, to shift.
voffset in, required double	The velocity offset (m/s) to add to the velocities (resulting velocities are then appropriate for a frame moving at voffset relative to the original frame of vel).

Keywords
veldef in, optional string (def. 'RADIO')	The velocity definition from one of RADIO, OPTICAL or TRUE.