tellipse

(./mat4/tellipse.m)

Function Synopsis

[htel,umi,ori]=tellipse(xc,yc,u,phi_u,v,phi_v,per,skip,sc,part_flag)

Help text

TELLIPSE plot ellipses from amp/phase specification of a vel field
 htel=tellipse(xc,yc,ua,up,va,vp,per,skip,sc,flag)

  TELLIPSE requires the following arguments:
      x    - ellipse x-coordinate centers, usually node x's;
      y    - ellipse y-coordinate centers, usually node y's;
      ua   - east (u) component amplitudes        
      up   - east (u) component phases (degrees)       
      va   - north (v) component amplitudes          
      vp   - north (v) component phases (degrees)        
      per  - period of field in hours

  TELLIPSE allows the following optional arguments:
      skip - number of nodes to skip in subsampling field
      sc   - scaling factor to use if per is 0.
      flag - flag for particle-excursion interpretation (0|1)
 
      NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE
      IF THE SCALING FACTOR NEEDS TO BE SPECIFIED, SKIP
      MUST ALSO BE SPECIFIED.  IF FLAG IS SPECIFIED, 
      SC AND SKIP MUST BE SPECIFIED, BOTH OF WHICH CAN BE SET
      TO 1.

  TELLIPSE scales the ellipses to 10% of the x-axis length 
  if sc=1; this is the default.  If sc=.5, the ellipse 
  magnitudes are scaled to 5% of the x-axis length,
  in the same manner as VECPLOT.  

  TELLIPSE expects the input phases to be in degrees and 
  attemps to determine the units of the phaselag by computing
  the range of the phaselag columns in the input matrix.
  If this range is within [0,2*pi], TELLIPSE reports this as
  a potential problem.  It does NOT abort due to the possibility
  of the phaselags correctly being in degrees and still having
  a range within [0,2*pi].

  NOTES: 1) TELLIPSE plots CCW ellipses in blue and CW ellipses 
            in red.
         2) TELLIPSE requires atleast 2 points and vectors.

 Call as: htel=tellipse(x,y,ua,up,va,vp,per,skip,sc,flag);

 Written by : Brian O. Blanton