Add all the A tasks

Task/Arithmetic-Complex/Fortran/arithmetic-complex-1.f

@@ -0,0 +1,9 @@
+program cdemo
+    complex :: a = (5,3), b = (0.5, 6.0)      ! complex initializer
+    complex :: absum, abprod, aneg, ainv
+
+    absum  = a + b
+    abprod = a * b
+    aneg   = -a
+    ainv   = 1.0 / a
+end program cdemo

Task/Arithmetic-Complex/Fortran/arithmetic-complex-2.f

@@ -0,0 +1,28 @@
+program cdemo2
+    complex :: a = (5,3), b = (0.5, 6)        ! complex initializer
+    real, parameter :: pi = 3.141592653589793 ! The constant "pi"
+    complex, parameter :: i = (0, 1)          ! the imaginary unit "i" (sqrt(-1))
+    complex :: abdiff, abquot, abpow, aconj, p2cart, newc
+    real :: areal, aimag, anorm, rho = 10, theta = pi / 3.0, x = 2.3, y = 3.0
+    integer, parameter :: n = 50
+    integer :: j
+    complex, dimension(0:n-1) :: unit_circle
+
+    abdiff = a - b
+    abquot = a / b
+    abpow  = a ** b
+    areal = real(a)               ! Real part
+    aimag = imag(a)               ! Imaginary part
+    newc = cmplx(x,y)             ! Creating a complex on the fly from two reals intrinsically
+                                  !   (initializer only works in declarations)
+    newc = x + y*i                ! Creating a complex on the fly from two reals arithmetically
+    anorm = abs(a)                ! Complex norm (or "modulus" or "absolute value")
+                                  !   (use CABS before Fortran 90)
+    aconj = conjg(a)              ! Complex conjugate (same as real(a) - i*imag(a))
+    p2cart = rho * exp(i * theta) ! Euler's polar complex notation to cartesian complex notation
+                                  !   conversion (use CEXP before Fortran 90)
+
+    ! The following creates an array of N evenly spaced points around the complex unit circle
+    ! useful for FFT calculations, among other things
+    unit_circle = exp(2*i*pi/n * (/ (j, j=0, n-1) /) )
+end program cdemo2