rpl.rb/lib/core/trig.rb

# frozen_string_literal: true

module Lang
  module Core
    module_function

    # pi constant
    def pi
      @stack << { type: :numeric,
                  base: 10,
                  value: BigMath.PI( precision ) }
    end

    # sinus
    def sinus
      args = stack_extract( [%i[numeric]] )

      @stack << { type: :numeric,
                  base: infer_resulting_base( args ),
                  value: BigMath.sin( BigDecimal( args[0][:value], precision ), precision ) }
    end

    # https://rosettacode.org/wiki/Trigonometric_functions#Ruby
    # arg sinus
    def arg_sinus
      run( '
  dup abs 1 ==
  « 𝛑 2 / * »
  « dup sq 1 swap - sqrt / atan »
  ifte' )
    end

    # cosinus
    def cosinus
      args = stack_extract( [%i[numeric]] )

      @stack << { type: :numeric,
                  base: infer_resulting_base( args ),
                  value: BigMath.cos( BigDecimal( args[0][:value], precision ), precision ) }
    end

    # arg cosinus
    def arg_cosinus
      run( '
  dup 0 ==
  « drop 𝛑 2 / »
  «
    dup sq 1 swap - sqrt / atan
    dup 0 <
    « 𝛑 + »
    ift
  »
  ifte' )
    end

    # tangent
    def tangent
      run( 'dup sin swap cos /' )
    end

    # arg tangent
    def arg_tangent
      args = stack_extract( [%i[numeric]] )

      @stack << { type: :numeric,
                  base: infer_resulting_base( args ),
                  value: BigMath.atan( BigDecimal( args[0][:value], precision ), precision ) }
    end

    # convert degrees to radians
    def degrees_to_radians
      run( '180 / 𝛑 *' )
    end

    # convert radians to degrees
    def radians_to_degrees
      run( '𝛑 180 / /' )
    end
  end
end