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[ferret_users] vector/aspect changes for the same velocity



Dear Ferreters,

I overlaid multiple VECTOR/ASPECT plots of a single velocity field and accidentally plotted the same vectors twice. To my surprise they had different angles!

If you look at the arrows at z = 95.74 m in the attached plot, the blue and red arrows are supposed to be identical but they are very different.  (The nearest data points are at 84.2 m and 108.00 m, which are far enough from 95.74 m we are looking at.)  Both are plotted with ASPECT.  The sample script and data are also attached.

I also wonder about a totally peripheral issue.  I thought PPL WINDOW,OFF refers to the plotting area.  But the attached script and plot suggest that the window-edge truncation is carried out according to the box of x=X1:X2/z=Z1:Z2 rather than the axes.  The blue arrows are truncated at z=300m. I would think truncating graphics elements at the edges of x= and z= isn't very intuitive.

I use

  NOAA/PMEL TMAP
  FERRET v7.3 (optimized)
  Linux 2.6.32-696.13.2.el6.x86_64 64-bit - 12/04/17
  4-Mar-18 22:07

on a Linux machine.

Regards,
Ryo

!==== Sample script =============
set mode grat:dash
set data mv-mw.nc

let fac = 1e3 ! velocity-length scale

define symbol y1_ 31S
define symbol y2_ 27S
let z2_ = 900

!-------
!go init-print

let samp_vec_in_ = 0.35
let samp_vec_ = fac/200

vector/aspect/hlimits=30S:28S/vlimits=0:900:20/y=($y1_):($y2_)/nolabel/color=red\
/z=0:100/set mv,mw
  ppl vecset,`samp_vec_in_`,`samp_vec_`
ppl vector,4,3
vector/aspect/y=($y1_):($y2_)/nolabel/color=blue\
/z=94:300/set mv,mw
  ppl vecset,`samp_vec_in_`,`samp_vec_`
ppl vector/ov,4,1
vector/aspect/y=($y1_):($y2_)/nolabel/color=red\
/z=300:`z2_`\
/set mv,mw
  ppl vecset,`samp_vec_in_`,`samp_vec_`
ppl vector/ov,4,1

!go finish-print try-vector-overlay 3 false
!=== END of script ====


Attachment: mv-mw.nc
Description: Binary data

Attachment: try-vector-overlay.pdf
Description: Adobe PDF document


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