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-#
-# complex.rb -
-# $Release Version: 0.5 $
-# $Revision: 1.3 $
-# $Date: 1998/07/08 10:05:28 $
-# by Keiju ISHITSUKA(SHL Japan Inc.)
-#
-# ----
-#
-# complex.rb implements the Complex class for complex numbers. Additionally,
-# some methods in other Numeric classes are redefined or added to allow greater
-# interoperability with Complex numbers.
-#
-# Complex numbers can be created in the following manner:
-# - <tt>Complex(a, b)</tt>
-# - <tt>Complex.polar(radius, theta)</tt>
-#
-# Additionally, note the following:
-# - <tt>Complex::I</tt> (the mathematical constant <i>i</i>)
-# - <tt>Numeric#im</tt> (e.g. <tt>5.im -> 0+5i</tt>)
-#
-# The following +Math+ module methods are redefined to handle Complex arguments.
-# They will work as normal with non-Complex arguments.
-# sqrt exp cos sin tan log log10 atan2
-#
-
-
-#
-# Creates a Complex number. +a+ and +b+ should be Numeric. The result will be
-# <tt>a+bi</tt>.
-#
-def Complex(a, b = 0)
- if a.kind_of?(Complex) and b == 0
- a
- elsif b.kind_of?(Complex)
- if a.kind_of?(Complex)
- Complex(a.real-b.image, a.image + b.real)
- else
- Complex(a-b.image, b.real)
- end
- elsif b == 0 and defined? Complex::Unify
- a
- else
- Complex.new!(a, b)
- end
-end
-
-#
-# The complex number class. See complex.rb for an overview.
-#
-class Complex < Numeric
- @RCS_ID='-$Id: complex.rb,v 1.3 1998/07/08 10:05:28 keiju Exp keiju $-'
-
- undef step
-
- def Complex.generic?(other) # :nodoc:
- other.kind_of?(Integer) or
- other.kind_of?(Float) or
- (defined?(Rational) and other.kind_of?(Rational))
- end
-
- #
- # Creates a +Complex+ number in terms of +r+ (radius) and +theta+ (angle).
- #
- def Complex.polar(r, theta)
- Complex(r*Math.cos(theta), r*Math.sin(theta))
- end
-
- private_class_method :new
- #
- # Creates a +Complex+ number <tt>a</tt>+<tt>b</tt><i>i</i>.
- #
- def Complex.new!(a, b=0)
- new(a,b)
- end
-
- def initialize(a, b)
- raise "non numeric 1st arg `#{a.inspect}'" if !a.kind_of? Numeric
- raise "non numeric 2nd arg `#{b.inspect}'" if !b.kind_of? Numeric
- @real = a
- @image = b
- end
-
- #
- # Addition with real or complex number.
- #
- def + (other)
- if other.kind_of?(Complex)
- re = @real + other.real
- im = @image + other.image
- Complex(re, im)
- elsif Complex.generic?(other)
- Complex(@real + other, @image)
- else
- x , y = other.coerce(self)
- x + y
- end
- end
-
- #
- # Subtraction with real or complex number.
- #
- def - (other)
- if other.kind_of?(Complex)
- re = @real - other.real
- im = @image - other.image
- Complex(re, im)
- elsif Complex.generic?(other)
- Complex(@real - other, @image)
- else
- x , y = other.coerce(self)
- x - y
- end
- end
-
- #
- # Multiplication with real or complex number.
- #
- def * (other)
- if other.kind_of?(Complex)
- re = @real*other.real - @image*other.image
- im = @real*other.image + @image*other.real
- Complex(re, im)
- elsif Complex.generic?(other)
- Complex(@real * other, @image * other)
- else
- x , y = other.coerce(self)
- x * y
- end
- end
-
- #
- # Division by real or complex number.
- #
- def / (other)
- if other.kind_of?(Complex)
- self*other.conjugate/other.abs2
- elsif Complex.generic?(other)
- Complex(@real/other, @image/other)
- else
- x, y = other.coerce(self)
- x/y
- end
- end
-
- #
- # Raise this complex number to the given (real or complex) power.
- #
- def ** (other)
- if other == 0
- return Complex(1)
- end
- if other.kind_of?(Complex)
- r, theta = polar
- ore = other.real
- oim = other.image
- nr = Math.exp!(ore*Math.log!(r) - oim * theta)
- ntheta = theta*ore + oim*Math.log!(r)
- Complex.polar(nr, ntheta)
- elsif other.kind_of?(Integer)
- if other > 0
- x = self
- z = x
- n = other - 1
- while n != 0
- while (div, mod = n.divmod(2)
- mod == 0)
- x = Complex(x.real*x.real - x.image*x.image, 2*x.real*x.image)
- n = div
- end
- z *= x
- n -= 1
- end
- z
- else
- if defined? Rational
- (Rational(1) / self) ** -other
- else
- self ** Float(other)
- end
- end
- elsif Complex.generic?(other)
- r, theta = polar
- Complex.polar(r.power!(other), theta * other)
- else
- x, y = other.coerce(self)
- x**y
- end
- end
-
- #
- # Remainder after division by a real or complex number.
- #
- def % (other)
- if other.kind_of?(Complex)
- Complex(@real % other.real, @image % other.image)
- elsif Complex.generic?(other)
- Complex(@real % other, @image % other)
- else
- x , y = other.coerce(self)
- x % y
- end
- end
-
-#--
-# def divmod(other)
-# if other.kind_of?(Complex)
-# rdiv, rmod = @real.divmod(other.real)
-# idiv, imod = @image.divmod(other.image)
-# return Complex(rdiv, idiv), Complex(rmod, rmod)
-# elsif Complex.generic?(other)
-# Complex(@real.divmod(other), @image.divmod(other))
-# else
-# x , y = other.coerce(self)
-# x.divmod(y)
-# end
-# end
-#++
-
- #
- # Absolute value (aka modulus): distance from the zero point on the complex
- # plane.
- #
- def abs
- Math.hypot(@real, @image)
- end
-
- #
- # Square of the absolute value.
- #
- def abs2
- @real*@real + @image*@image
- end
-
- #
- # Argument (angle from (1,0) on the complex plane).
- #
- def arg
- Math.atan2(@image.to_f, @real.to_f)
- end
-
- #
- # Returns the absolute value _and_ the argument.
- #
- def polar
- return abs, arg
- end
-
- #
- # Complex conjugate (<tt>z + z.conjugate = 2 * z.real</tt>).
- #
- def conjugate
- Complex(@real, -@image)
- end
-
- #
- # Compares the absolute values of the two numbers.
- #
- def <=> (other)
- self.abs <=> other.abs
- end
-
- #
- # Test for numerical equality (<tt>a == a + 0<i>i</i></tt>).
- #
- def == (other)
- if other.kind_of?(Complex)
- @real == other.real and @image == other.image
- elsif Complex.generic?(other)
- @real == other and @image == 0
- else
- other == self
- end
- end
-
- #
- # Attempts to coerce +other+ to a Complex number.
- #
- def coerce(other)
- if Complex.generic?(other)
- return Complex.new!(other), self
- else
- super
- end
- end
-
- #
- # FIXME
- #
- def denominator
- @real.denominator.lcm(@image.denominator)
- end
-
- #
- # FIXME
- #
- def numerator
- cd = denominator
- Complex(@real.numerator*(cd/@real.denominator),
- @image.numerator*(cd/@image.denominator))
- end
-
- #
- # Standard string representation of the complex number.
- #
- def to_s
- if @real != 0
- if defined?(Rational) and @image.kind_of?(Rational) and @image.denominator != 1
- if @image >= 0
- @real.to_s+"+("+@image.to_s+")i"
- else
- @real.to_s+"-("+(-@image).to_s+")i"
- end
- else
- if @image >= 0
- @real.to_s+"+"+@image.to_s+"i"
- else
- @real.to_s+"-"+(-@image).to_s+"i"
- end
- end
- else
- if defined?(Rational) and @image.kind_of?(Rational) and @image.denominator != 1
- "("+@image.to_s+")i"
- else
- @image.to_s+"i"
- end
- end
- end
-
- #
- # Returns a hash code for the complex number.
- #
- def hash
- @real.hash ^ @image.hash
- end
-
- #
- # Returns "<tt>Complex(<i>real</i>, <i>image</i>)</tt>".
- #
- def inspect
- sprintf("Complex(%s, %s)", @real.inspect, @image.inspect)
- end
-
-
- #
- # +I+ is the imaginary number. It exists at point (0,1) on the complex plane.
- #
- I = Complex(0,1)
-
- # The real part of a complex number.
- attr :real
-
- # The imaginary part of a complex number.
- attr :image
- alias imag image
-
-end
-
-
-#
-# Numeric is a built-in class on which Fixnum, Bignum, etc., are based. Here
-# some methods are added so that all number types can be treated to some extent
-# as Complex numbers.
-#
-class Numeric
- #
- # Returns a Complex number <tt>(0,<i>self</i>)</tt>.
- #
- def im
- Complex(0, self)
- end
-
- #
- # The real part of a complex number, i.e. <i>self</i>.
- #
- def real
- self
- end
-
- #
- # The imaginary part of a complex number, i.e. 0.
- #
- def image
- 0
- end
- alias imag image
-
- #
- # See Complex#arg.
- #
- def arg
- if self >= 0
- return 0
- else
- return Math::PI
- end
- end
-
- #
- # See Complex#polar.
- #
- def polar
- return abs, arg
- end
-
- #
- # See Complex#conjugate (short answer: returns <i>self</i>).
- #
- def conjugate
- self
- end
-end
-
-
-class Fixnum
- unless defined? 1.power!
- alias power! **
- p [__FILE__, defined? 1.power!]
- end
-
- # Redefined to handle a Complex argument.
- def ** (other)
- if self < 0
- Complex.new!(self, 0) ** other
- else
- if defined? self.rpower
- self.rpower(other)
- else
- self.power!(other)
- end
- end
- end
-end
-
-class Bignum
- alias power! **
-end
-
-class Float
- alias power! **
-end
-
-module Math
- alias sqrt! sqrt
- alias exp! exp
- alias cos! cos
- alias sin! sin
- alias tan! tan
- alias log! log
- alias atan! atan
- alias log10! log10
- alias atan2! atan2
-
- # Redefined to handle a Complex argument.
- def sqrt(z)
- if Complex.generic?(z)
- if z >= 0
- sqrt!(z)
- else
- Complex(0,sqrt!(-z))
- end
- else
- if z.image < 0
- sqrt(z.conjugate).conjugate
- else
- r = z.abs
- x = z.real
- Complex( sqrt!((r+x)/2), sqrt!((r-x)/2) )
- end
- end
- end
-
- # Redefined to handle a Complex argument.
- def exp(z)
- if Complex.generic?(z)
- exp!(z)
- else
- Complex(exp!(z.real) * cos!(z.image), exp!(z.real) * sin!(z.image))
- end
- end
-
- #
- # Hyperbolic cosine.
- #
- def cosh!(x)
- (exp!(x) + exp!(-x))/2.0
- end
-
- #
- # Hyperbolic sine.
- #
- def sinh!(x)
- (exp!(x) - exp!(-x))/2.0
- end
-
- # Redefined to handle a Complex argument.
- def cos(z)
- if Complex.generic?(z)
- cos!(z)
- else
- Complex(cos!(z.real)*cosh!(z.image),
- -sin!(z.real)*sinh!(z.image))
- end
- end
-
- # Redefined to handle a Complex argument.
- def sin(z)
- if Complex.generic?(z)
- sin!(z)
- else
- Complex(sin!(z.real)*cosh!(z.image),
- cos!(z.real)*sinh!(z.image))
- end
- end
-
- # Redefined to handle a Complex argument.
- def tan(z)
- if Complex.generic?(z)
- tan!(z)
- else
- sin(z)/cos(z)
- end
- end
-
- # Redefined to handle a Complex argument.
- def log(z)
- if Complex.generic?(z) and z >= 0
- log!(z)
- else
- r, theta = z.polar
- Complex(log!(r.abs), theta)
- end
- end
-
- # Redefined to handle a Complex argument.
- def log10(z)
- if Complex.generic?(z)
- log10!(z)
- else
- log(z)/log!(10)
- end
- end
-
- # FIXME: I don't know what the point of this is. If you give it Complex
- # arguments, it will fail.
- def atan2(x, y)
- if Complex.generic?(x) and Complex.generic?(y)
- atan2!(x, y)
- else
- fail "Not yet implemented."
- end
- end
-
- #
- # Hyperbolic arctangent.
- #
- def atanh!(x)
- log((1.0 + x.to_f) / ( 1.0 - x.to_f)) / 2.0
- end
-
- # Redefined to handle a Complex argument.
- def atan(z)
- if Complex.generic?(z)
- atan2!(z, 1)
- elsif z.image == 0
- atan2(z.real,1)
- else
- a = z.real
- b = z.image
-
- c = (a*a + b*b - 1.0)
- d = (a*a + b*b + 1.0)
-
- Complex(atan2!((c + sqrt(c*c + 4.0*a*a)), 2.0*a),
- atanh!((-d + sqrt(d*d - 4.0*b*b))/(2.0*b)))
- end
- end
-
- module_function :sqrt
- module_function :sqrt!
- module_function :exp!
- module_function :exp
- module_function :cosh!
- module_function :cos!
- module_function :cos
- module_function :sinh!
- module_function :sin!
- module_function :sin
- module_function :tan!
- module_function :tan
- module_function :log!
- module_function :log
- module_function :log10!
- module_function :log
- module_function :atan2!
- module_function :atan2
-# module_function :atan!
- module_function :atan
- module_function :atanh!
-
-end
-
-# Documentation comments:
-# - source: original (researched from pickaxe)
-# - a couple of fixme's
-# - Math module methods sinh! etc. a bit fuzzy. What exactly is the intention?
-# - RDoc output for Bignum etc. is a bit short, with nothing but an
-# (undocumented) alias. No big deal.