Manual Reference Pages - huge (3fortran)

NAME

HUGE(3) - [NUMERIC MODEL] Largest number of a type and kind

SYNOPSIS

result = huge(x)

         TYPE(kind=KIND) function huge(x)

          TYPE(kind=KIND),intent(in) :: x(..)

CHARACTERISTICS

o X may be any real or integer scalar or array and any kind.

o The result will be a scalar of the same type and kind as the input X

DESCRIPTION

HUGE(3) returns the largest number that is not an overflow for the kind and type of X.

OPTIONS

o X : X is an arbitrary value which is used merely to determine what kind and type of scalar is being queried. It need not be defined, as only its characteristics are used.

RESULT

The result is the largest value supported by the specified type and kind.
Note the result is as the same kind as the input to ensure the returned value does not overflow. Any assignment of the result to a variable should take this into consideration.

EXAMPLES

Sample program:

    program demo_huge
    implicit none
    character(len=*),parameter :: f=’(i2,1x,2(i11,1x),f14.0:,1x,l1,1x,a)’
    integer :: i,j,k,biggest
    real :: v, w
    doubleprecision :: tally
       ! basic
       print *, huge(0), huge(0.0), huge(0.0d0)
       print *, tiny(0.0), tiny(0.0d0)

       tally=0.0d0
       ! note subtracting one because counter is the end value+1 on exit
       do i=0,huge(0)-1
          tally=tally+i
       enddo
       write(*,*)’tally=’,tally

       ! advanced
       biggest=huge(0)
       ! be careful of overflow when using integers in computation
       do i=1,14
          j=6**i   ! Danger, Danger
          w=6**i   ! Danger, Danger
          v=6.0**i
          k=v      ! Danger, Danger

          if(v.gt.biggest)then
             write(*,f) i, j, k, v, v.eq.w, ’wrong j and k and w’
          else
             write(*,f) i, j, k, v, v.eq.w
          endif

       enddo
    end program demo_huge

Results:

2147483647 3.4028235E+38 1.797693134862316E+308 1.1754944E-38 2.225073858507201E-308

1 6 6 6. T 2 36 36 36. T 3 216 216 216. T 4 1296 1296 1296. T 5 7776 7776 7776. T 6 46656 46656 46656. T 7 279936 279936 279936. T 8 1679616 1679616 1679616. T 9 10077696 10077696 10077696. T 10 60466176 60466176 60466176. T 11 362797056 362797056 362797056. T 12 -2118184960 -2147483648 2176782336. F wrong for j and k and w 13 175792128 -2147483648 13060694016. F wrong for j and k and w 14 1054752768 -2147483648 78364164096. F wrong for j and k and w

STANDARD

Fortran 95

o	X may be any real or integer scalar or array and any kind.
o	The result will be a scalar of the same type and kind as the input X