Difference between revisions of "ATAN2"

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{{DISPLAYTITLE:_ATAN2}}
 
{{DISPLAYTITLE:_ATAN2}}
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The '''_ATAN2''' function returns the radian angle between the positive x-axis of a plane and the point given by the coordinates (x, y) on it.
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The [[_ATAN2]] function returns the radian angle between the positive x-axis of a plane and the point given by the coordinates (x, y).
  
  
 
{{PageSyntax}}
 
{{PageSyntax}}
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::: angle! = '''_ATAN2(''' ''y'', ''x''''')'''
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: {{Parameter|angle!}} = [[_ATAN2]]({{Parameter|y}}, {{Parameter|x}})
  
  
 
{{Parameters}}
 
{{Parameters}}
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* ''y'' is the vertical axis position(row).
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* {{Parameter|y}} is the vertical axis position (row) as a positive, zero or negative floating point value.
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* ''x'' is the horizontal axis position(column).  
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* {{Parameter|x}} is the horizontal axis position (column) as a positive, zero or negative floating point value.  
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{{PageDescription}}
 
{{PageDescription}}
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* The [[DOUBLE]] radian angle returned is positive for upper row values where y > 0.
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* The [[DOUBLE]] radian angle returned is '''positive''' for upper row values where y > 0.
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* The [[DOUBLE]] radian angle returned is negative for lower row values where y < 0.
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::* _ATAN2(y, x) = [[ATN]](y# / x#) when x > 0
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* _ATAN2(y, x) = [[ATN]](y / x) when x > 0
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::* _ATAN2(y, x) = [[ATN]](y# / x#) + [[_PI]] when x < 0
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* _ATAN2(y, x) = [[ATN]](y / x) + [[_PI]] when x < 0 and y >= 0
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::* _ATAN2(y, x) = [[_PI]] / 2 when x = 0
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* _ATAN2(y, x) = [[ATN]](y / x) - [[_PI]] when x < 0 and y < 0
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* The [[DOUBLE]] radian angle returned is 0 when x > 0 and [[_PI]] when x < 0 where y = 0
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* _ATAN2(y' x) = [[_PI]] / 2 when x = 0 and y > 0
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* The [[DOUBLE]] radian angle returned is '''negative''' for lower row values where y < 0.
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* _ATAN2(y, x) = -[[_PI]] / 2 when x = 0 and y < 0
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::* _ATAN2(y, x) = [[ATN]](y# / x#) when x > 0
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* _ATAN2(0, 0) is undefined and the function returns 0.
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::* _ATAN2(y, x) = [[ATN]](y# / x#) - [[_PI]] when x < 0
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::* _ATAN2(y, x) = -[[_PI]] / 2 when x = 0
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* _ATAN2(0, 0) is undefined and the function returns 0 instead of a division error.
  
  
 
{{PageErrors}}
 
{{PageErrors}}
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* Note: With [[ATN]](y / x), x can never be 0! That would create a Division by Zero [[ERROR Codes|error]].
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* With [[ATN]](y / x), x can never be 0 as that would create a Division by Zero [[ERROR Codes|error]] 11 or #IND.
  
  
 
{{PageSeeAlso}}
 
{{PageSeeAlso}}
 
* [[ATN]] {{text|(arctangent)}}
 
* [[ATN]] {{text|(arctangent)}}
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* [[_PI]] {{text|(QB64 constant value)}}
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* [[_PI]] {{text|(QB64 function)}}
 
* [[Mathematical Operations]]
 
* [[Mathematical Operations]]
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* [https://en.wikipedia.org/wiki/Atan2 Atan2 reference]
  
  
 
{{PageNavigation}}
 
{{PageNavigation}}

Revision as of 13:26, 5 September 2017

The _ATAN2 function returns the radian angle between the positive x-axis of a plane and the point given by the coordinates (x, y).


Syntax

angle! = _ATAN2(y, x)


Parameters

  • y is the vertical axis position (row) as a positive, zero or negative floating point value.
  • x is the horizontal axis position (column) as a positive, zero or negative floating point value.


Description

  • The DOUBLE radian angle returned is positive for upper row values where y > 0.
  • _ATAN2(y, x) = ATN(y# / x#) when x > 0
  • _ATAN2(y, x) = ATN(y# / x#) + _PI when x < 0
  • _ATAN2(y, x) = _PI / 2 when x = 0
  • The DOUBLE radian angle returned is 0 when x > 0 and _PI when x < 0 where y = 0
  • The DOUBLE radian angle returned is negative for lower row values where y < 0.
  • _ATAN2(y, x) = ATN(y# / x#) when x > 0
  • _ATAN2(y, x) = ATN(y# / x#) - _PI when x < 0
  • _ATAN2(y, x) = -_PI / 2 when x = 0
  • _ATAN2(0, 0) is undefined and the function returns 0 instead of a division error.


Errors

  • With ATN(y / x), x can never be 0 as that would create a Division by Zero error 11 or #IND.


See also


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