module Data.Complex(Complex((:+)), realPart, imagPart, conjugate, mkPolar,
                     cis, polar, magnitude, phase)  where
 
 infix  6  :+
 
 data  (RealFloat a)     => Complex a = !a :+ !a  deriving (Eq,Read,Show)
 
 
 realPart, imagPart :: (RealFloat a) => Complex a -> a
 realPart (x:+y)        =  x
 imagPart (x:+y)        =  y
 
 conjugate      :: (RealFloat a) => Complex a -> Complex a
 conjugate (x:+y) =  x :+ (-y)
 
 mkPolar                :: (RealFloat a) => a -> a -> Complex a
 mkPolar r theta        =  r * cos theta :+ r * sin theta
 
 cis            :: (RealFloat a) => a -> Complex a
 cis theta      =  cos theta :+ sin theta
 
 polar          :: (RealFloat a) => Complex a -> (a,a)
 polar z                =  (magnitude z, phase z)
 
 magnitude :: (RealFloat a) => Complex a -> a
 magnitude (x:+y) =  scaleFloat k
                    (sqrt ((scaleFloat mk x)^2 + (scaleFloat mk y)^2))
                   where k  = max (exponent x) (exponent y)
                         mk = - k
 
 phase :: (RealFloat a) => Complex a -> a
 phase (0 :+ 0) = 0
 phase (x :+ y) = atan2 y x
 
 
 instance  (RealFloat a) => Num (Complex a)  where
     (x:+y) + (x':+y') =  (x+x') :+ (y+y')
     (x:+y) - (x':+y') =  (x-x') :+ (y-y')
     (x:+y) * (x':+y') =  (x*x'-y*y') :+ (x*y'+y*x')
     negate (x:+y)     =  negate x :+ negate y
     abs z             =  magnitude z :+ 0
     signum 0          =  0
     signum z@(x:+y)   =  x/r :+ y/r  where r = magnitude z
     fromInteger n     =  fromInteger n :+ 0
 
 instance  (RealFloat a) => Fractional (Complex a)  where
     (x:+y) / (x':+y') =  (x*x''+y*y'') / d :+ (y*x''-x*y'') / d
                          where x'' = scaleFloat k x'
                                y'' = scaleFloat k y'
                                k   = - max (exponent x') (exponent y')
                                d   = x'*x'' + y'*y''

     fromRational a    =  fromRational a :+ 0
 
 instance  (RealFloat a) => Floating (Complex a)       where
     pi             =  pi :+ 0
     exp (x:+y)     =  expx * cos y :+ expx * sin y
                       where expx = exp x
     log z          =  log (magnitude z) :+ phase z
 
     sqrt 0         =  0
     sqrt z@(x:+y)  =  u :+ (if y < 0 then -v else v)
                       where (u,v) = if x < 0 then (v',u') else (u',v')
                             v'    = abs y / (u'*2)
                             u'    = sqrt ((magnitude z + abs x) / 2)
 
     sin (x:+y)     =  sin x * cosh y :+ cos x * sinh y
     cos (x:+y)     =  cos x * cosh y :+ (- sin x * sinh y)
     tan (x:+y)     =  (sinx*coshy:+cosx*sinhy)/(cosx*coshy:+(-sinx*sinhy))
                       where sinx  = sin x
                             cosx  = cos x
                             sinhy = sinh y
                             coshy = cosh y
 
     sinh (x:+y)    =  cos y * sinh x :+ sin  y * cosh x
     cosh (x:+y)    =  cos y * cosh x :+ sin y * sinh x
     tanh (x:+y)    =  (cosy*sinhx:+siny*coshx)/(cosy*coshx:+siny*sinhx)
                       where siny  = sin y
                             cosy  = cos y
                             sinhx = sinh x
                             coshx = cosh x
 
     asin z@(x:+y)  =  y':+(-x')
                       where  (x':+y') = log (((-y):+x) + sqrt (1 - z*z))
     acos z@(x:+y)  =  y'':+(-x'')
                       where (x'':+y'') = log (z + ((-y'):+x'))
                             (x':+y')   = sqrt (1 - z*z)
     atan z@(x:+y)  =  y':+(-x')
                       where (x':+y') = log (((1-y):+x) / sqrt (1+z*z))
 
     asinh z        =  log (z + sqrt (1+z*z))
     acosh z        =  log (z + (z+1) * sqrt ((z-1)/(z+1)))
     atanh z        =  log ((1+z) / sqrt (1-z*z))