;+
; NAME:
; UNITIZE
;
; AUTHOR:
; Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
; craigm@lheamail.gsfc.nasa.gov
; UPDATED VERSIONs can be found on my WEB PAGE:
; http://cow.physics.wisc.edu/~craigm/idl/idl.html
;
; PURPOSE:
; Construct a unit vector from a vector
;
; MAJOR TOPICS:
; Geometry
;
; CALLING SEQUENCE:
; U = UNITIZE(V)
;
; DESCRIPTION:
;
; The function UNITIZE accepts any vector as input, and returns a
; unit vector. The returned vector has the same direction as V but
; a unit magnitude. (using L2 norm)
;
; Mostly commonly UNITIZE will be used on 3-vectors. The input V
; may either be a single 3-vector (i.e. DBLARR(3)) or it may be an
; array of N 3-vectors, (i.e. DBLARR(3,N)). The returned array will
; have the same structure as V.
;
; UNITIZE also works on vectors with arbitrary numbers of
; components. All that is required is that the vector components be
; the first dimension of the input array V.
;
; INPUTS:
;
; V - input array, commonly a 3-vector for a single vector, or a 3xN
; array for N vectors. It is also possible to pass any array
; DBLARR(M,n1,n2,n3,...).
;
;
; RETURNS:
;
; The resulting unitized vector or vectors. The output has the same
; dimension as the input, V.
;
;
; KEYWORD PARAMETERS:
;
; NONE
;
; EXAMPLE:
;
; print, unitize([3d,4d,0d])
; ==> [0.6, 0.8, 0.0]
;
; SEE ALSO
; UNITVECANG, ANGUNITVEC, CROSSP, QTNORMALIZE
;
; MODIFICATION HISTORY:
; Written, 1999, CM
; Converted to more general dimension, 2012-10-02, CM
; Documented, 2012-10-02, CM
;
; $Id: unitize.pro,v 1.5 2012/10/02 12:28:47 cmarkwar Exp $
;
;-
; Copyright (C) 1999, 2012, Craig Markwardt
; This software is provided as is without any warranty whatsoever.
; Permission to use, copy, modify, and distribute modified or
; unmodified copies is granted, provided this copyright and disclaimer
; are included unchanged.
;-
function unitize, u, magnitude=uu
uu = sqrt(total(u^2,1))
nu = n_elements(uu)
if nu EQ 1 then return, u/uu(0)
nv = n_elements(u)/nu
uu3 = u
for i = 0, nv-1 do uu3(i,*) = uu
return, u / uu3
end