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92 lines
3 KiB
Plaintext
92 lines
3 KiB
Plaintext
{{QBDLDATE:05-20-2022}}
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{{QBDLTIME:23:11:52}}
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The [[ATN]] or arctangent function returns the angle in radians of a numerical [[TAN|tangent]] value.
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{{PageSyntax}}
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: {{Parameter|radianAngle}} = [[ATN]]({{Parameter|tangent!}})
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{{Parameters}}
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* The return is the {{Parameter|tangent!}}'s angle in '''radians'''.
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* {{Parameter|tangent!}} [[SINGLE]] or [[DOUBLE]] values are used by the function. EX:'''{{text|Pi <nowiki>=</nowiki> 4 * ATN(1)|green}}'''
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{{PageDescription}}
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* To convert from radians to degrees, multiply radians * (180 / ã).
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* The ''tangent'' value would be equal to the tangent value of an angle. Ex: '''{{text|[[TAN]](ATN(1)) <nowiki>=</nowiki> 1|green}}'''
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* The function return value is between -ã / 2 and ã / 2.
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{{PageExamples}}
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''Example 1:'' When the [[TAN]]gent value equals 1, the line is drawn at a 45 degree angle (.7853982 radians) where [[SIN]] / [[COS]] = 1.
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{{CodeStart}}
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{{Cl|SCREEN}} 12
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x = 100 * {{Cl|COS}}({{Cl|ATN}}(1))
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y = 100 * {{Cl|SIN}}({{Cl|ATN}}(1))
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{{Cl|LINE}} (200, 200)-(200 + x, 200 + y)
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{{CodeEnd}}
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''Example 2:'' [[ATN]] can be used to define ã in [[SINGLE]] or [[DOUBLE]] precision. The calculation cannot be used as a [[CONST]]ant.
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{{CodeStart}}
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Pi = 4 * {{Cl|ATN}}(1) '{{Cl|SINGLE}} precision
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Pi# = 4 * {{Cl|ATN}}(1#) '{{Cl|DOUBLE}} precision
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PRINT Pi, Pi#
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{{CodeEnd}}
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:''Note:'' You can use QB64's native [[_PI]] function.
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''Example 3:'' Finds the angle from the center point to the mouse pointer.
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{{CodeStart}}
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{{Cl|SCREEN}} {{Cl|_NEWIMAGE}}(640, 480, 32)
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x1! = 320
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y1! = 240
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DO
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{{Cl|PRESET}} (x1!, y1!), {{Cl|_RGB}}(255, 255, 255)
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dummy% = {{Cl|_MOUSEINPUT}}
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x2! = {{Cl|_MOUSEX}}
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y2! = {{Cl|_MOUSEY}}
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{{Cl|LINE}} (x1, y1)-(x2, y2), {{Cl|_RGB}}(255, 0, 0)
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{{Cl|LOCATE}} 1, 1: {{Cl|PRINT}} getangle(x1!, y1!, x2!, y2!)
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{{Cl|_DISPLAY}}
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{{Cl|_LIMIT}} 200
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{{Cl|CLS}}
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{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} <> ""
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{{Cl|END}}
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{{Cl|FUNCTION}} getangle# (x1#, y1#, x2#, y2#) 'returns 0-359.99...
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{{Cl|IF...THEN|IF}} y2# = y1# {{Cl|THEN}}
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{{Cl|IF...THEN|IF}} x1# = x2# {{Cl|THEN}} {{Cl|EXIT FUNCTION}}
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{{Cl|IF...THEN|IF}} x2# > x1# {{Cl|THEN}} getangle# = 90 {{Cl|ELSE}} getangle# = 270
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{{Cl|EXIT FUNCTION}}
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{{Cl|END IF}}
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{{Cl|IF...THEN|IF}} x2# = x1# {{Cl|THEN}}
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{{Cl|IF...THEN|IF}} y2# > y1# {{Cl|THEN}} getangle# = 180
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{{Cl|EXIT FUNCTION}}
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{{Cl|END IF}}
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{{Cl|IF...THEN|IF}} y2# < y1# {{Cl|THEN}}
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{{Cl|IF...THEN|IF}} x2# > x1# {{Cl|THEN}}
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getangle# = {{Cl|ATN}}((x2# - x1#) / (y2# - y1#)) * -57.2957795131
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{{Cl|ELSE}}
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getangle# = {{Cl|ATN}}((x2# - x1#) / (y2# - y1#)) * -57.2957795131 + 360
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{{Cl|END IF}}
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{{Cl|ELSE}}
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getangle# = {{Cl|ATN}}((x2# - x1#) / (y2# - y1#)) * -57.2957795131 + 180
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{{Cl|END IF}}
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{{Cl|END FUNCTION}}
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{{CodeEnd}}{{small|Function by Galleon}}
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{{PageSeeAlso}}
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* [[_PI]] {{text|(QB64 function)}}
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* [[TAN]] {{text|(tangent function)}}
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* [[SIN]], [[COS]]
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* [[Mathematical Operations]]
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* [[Mathematical_Operations#Derived_Mathematical_Functions|Derived Mathematical Functions]]
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{{PageNavigation}}
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