Difference between revisions of "ATAN2"

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{{PageSyntax}}
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==Syntax==
::: angle! = '''_ATAN2(''' ''y'', ''x''''')'''
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: {{Parameter|angle!}} = {{KW|_ATAN2}}({{Parameter|y}}, {{Parameter|x}})
  
  
{{Parameters}}
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===Parameters===
* ''y'' is the vertical axis position(row) as a positive, zero or negative floating point value.
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* {{Parameter|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.  
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* {{Parameter|x}} is the horizontal axis position (column) as a positive, zero or negative floating point value.  
  
  
{{PageDescription}}
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==Description==
 
 
 
* The [[DOUBLE]] radian angle returned is '''positive''' for upper row values where y > 0.
 
* 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#) when x > 0
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{{PageErrors}}
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===Errors===
* Note: With [[ATN]](y / x), x can never be 0 as that would create a Division by Zero [[ERROR Codes|error]] 11 or #IND.
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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}}
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==See also==
 
* [[ATN]] {{text|(arctangent)}}
 
* [[ATN]] {{text|(arctangent)}}
 
* [[_PI]] {{text|(QB64 function)}}
 
* [[_PI]] {{text|(QB64 function)}}

Revision as of 01:10, 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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