[postgis-devel] [PostGIS] #876: Better document ST_Azimuth

[PostGIS]

#876: Better document ST_Azimuth
----------------------------+-----------------------------------------------
  Reporter:  strk           |       Owner:  robe         
      Type:  task           |      Status:  reopened     
  Priority:  medium         |   Milestone:  PostGIS 2.0.0
 Component:  documentation  |     Version:  trunk        
Resolution:                 |    Keywords:               
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Changes (by wrog):

  * status:  closed => reopened
  * resolution:  fixed =>


Comment:

 Docs are still partially wrong and the diagram is wrong.
 {{{
 Returns the angle in radians from the horizontal of the vector defined by
 pointA and pointB.
 }}}
 should be
 {{{
 Returns the angle in radians clockwise from the vertical of the vector at
 pointA pointing in the direction of pointB.
 }}}
 Also, the gray line in the diagram should be pointing upwards from the
 center, not to the right, and it might also help if the yellow arc had an
 arrow pointing clockwise

 The "clock" portion of the description is, at least, correct.

 (...the problem is, I believe most people would expect this function to
 behave as diagrammed, with 3 o'clock being zero degress and 12 o'clock
 being pi/2, or at least that's the way we were all taught in math classes
 back in high school -- or at least that's the way US schools do it.  I've
 never before seen a from-the-vertical convention for 2D angles; is this a
 European convention?  or did somebody just goof when coding this function
 in the first place...)

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/876#comment:2>
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