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atan()

Calculates the arc tangent of a number.

atan() is the inverse of tan(). It expects input values in the range of -Infinity to Infinity. By default, atan() returns values in the range -π ÷ 2 (about -1.57) to π ÷ 2 (about 1.57). If the angleMode() is DEGREES then values are returned in the range -90 to 90.

Examples

atan example 1

function setup()
  size(100, 100)
  fill(0)

  background(200)

  -- Calculate tan() and atan() values.
  local a = PI / 3
  local t = tan(a)
  local at = atan(t)

  -- Display the values.
  text(round(a, 3), 35, 25)
  text(round(t, 3), 35, 50)
  text(round(at, 3), 35, 75)

  describe('The numbers 1.047, 1.732, and 1.047 printed on separate rows.')
end

atan example 2

function setup()
  size(100, 100)
  fill(0)

  background(200)

  -- Calculate tan() and atan() values.
  local a = PI + PI / 3
  local t = tan(a)
  local at = atan(t)

  -- Display the values.
  text(round(a, 3), 35, 25)
  text(round(t, 3), 35, 50)
  text(round(at, 3), 35, 75)

  describe('The numbers 4.189, 1.732, and 1.047 printed on separate rows.')
end

Syntax

atan(value)

Parameters

Parameter
value Number: value whose arc tangent is to be returned

Returns

Number: arc tangent of the given value