Floating point data types represent approximations to quantities in a
  scientific  notation  consisting  of a signed integer and a fraction.
  The four floating point data types are  the  32-bit  F_FLOATING,  the
  64-bit D_FLOATING, the 64-bit G_FLOATING, and the 128-bit H_FLOATING.
  In addition, you can  use  F_FLOATING  COMPLEX,  D_FLOATING  COMPLEX,
  G_FLOATING  COMPLEX,  and H_FLOATING COMPLEX to specify ordered pairs
  of floating point data types  representing  the  real  and  imaginary
  components of complex numbers.