8.230 SPACING — Smallest distance between two numbers of a given type

Description:
Determines the distance between the argument X and the nearest adjacent number of the same type.
Standard:
Fortran 95 and later
Class:
Elemental function
Syntax:
RESULT = SPACING(X)
Arguments:
X Shall be of type REAL.
Return value:
The result is of the same type as the input argument X.
Example:
PROGRAM test_spacing
  INTEGER, PARAMETER :: SGL = SELECTED_REAL_KIND(p=6, r=37)
  INTEGER, PARAMETER :: DBL = SELECTED_REAL_KIND(p=13, r=200)

  WRITE(*,*) spacing(1.0_SGL)      ! "1.1920929E-07"          on i686
  WRITE(*,*) spacing(1.0_DBL)      ! "2.220446049250313E-016" on i686
END PROGRAM
See also:
RRSPACING

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Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-4.9.3/gfortran/SPACING.html