Module: Kernel

Defined in:
lib/quaternion_c2/conversion.rb

Class Method Summary collapse

Class Method Details

.Quaternion(w, x, y, z) ⇒ Quaternion .Quaternion(a, b) ⇒ Quaternion .Quaternion(s, v) ⇒ Quaternion .Quaternion(str) ⇒ Quaternion

Returns a quaternion.

This function accepts various arguments except polar form. Strings are parsed to Numeric.

Examples:

Quaternion(1)            #=> (1+0i+0j+0k)
Quaternion(1, 2)         #=> (1+0i+2j+0k) # not (1+2i+0j+0k)
Quaternion(1, 2, 3, 4)   #=> (1+2i+3j+4k)
Quaternion(1, [2, 3, 4]) #=> (1+2i+3j+4k)
Quaternion('1+2i+3j+4k') #=> (1+2i+3j+4k)

Overloads:



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# File 'lib/quaternion_c2/conversion.rb', line 242

def Quaternion(*args)
	argc = args.size

	unless (1..4).cover?(argc)
		raise ArgumentError,
		      "wrong number of arguments (given #{argc}, expected 1..4)"
	end

	if args.any?(&:nil?)
		raise TypeError, "can't convert nil into Quaternion"
	end

	# convert String into Numeric (strictly)
	args.collect! do |arg|
		case arg
		when String
			Quaternion.send(:parse, arg, true)
		else
			arg
		end
	end

	case argc
	when 1
		arg = args[0]
		if arg.kind_of?(Numeric)
			# a quaternion (or an octonion, etc.)
			return arg.complex? ? arg.to_q : arg
		else
			raise TypeError,
			      "can't convert #{arg.class} into Quaternion"
		end
	when 2
		if args[1].kind_of?(Enumerable)
			# scalar and 3-D vector -> expand
			if args[1].size != 3
				raise TypeError, "not a 3-D vector"
			end
			args.flatten!(1)
		elsif args.all? { |x| x.kind_of?(Numeric) && x.complex? }
			# a pair of complex numbers
			return Quaternion.send(:new, *args)
		else
			return args[0] + args[1] * Quaternion::J
		end
	end

	w, x, y, z = args
	z ||= 0
	if args.all? { |x| x.kind_of?(Numeric) && x.real? }
		# 3 or 4 real numbers
		a = Complex.rect(w, x)
		b = Complex.rect(y, z)
		Quaternion.send(:new, a, b)
	else
		a = Complex(w, x)
		b = Complex(y, z)
		if [a, b].all? { |x| x.kind_of?(Numeric) && x.complex? }
			Quaternion.send(:new, a, b)
		else
			a + b * Quaternion::J
		end
	end
end