Manual Reference Pages - huge (3fortran)
HUGE(3) - [MODEL:NUMERIC] 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 requires the variable must be able to hold the value as well. For example:
real :: r r=huge(0.0d0)where R is single-precision would almost certainly result in overflow.
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)Results: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 ! a simple check of the product of two 32-bit integers print *,checkprod([2,4,5,8],[10000,20000,3000000,400000000])
contains impure elemental function checkprod(i,j) result(ij32) ! checkprod(3f) - check for overflow when multiplying 32-bit integers use,intrinsic :: iso_fortran_env, only : int8, int16, int32, int64 integer(kind=int32),intent(in) :: i, j integer(kind=int64) :: ij64 integer(kind=int32) :: ij32 integer,parameter :: toobig=huge(0_int32) character(len=80) :: message ij64=int(i,kind=int64)*int(j,kind=int64) if(ij64.gt.toobig)then write(message,’(*(g0))’)& & ’<ERROR>checkprod(3f):’,i,’*’,j,’=’,ij64,’>’,toobig stop message else ij32=ij64 endif end function checkprod end program demo_huge
> 2147483647 3.40282347E+38 1.7976931348623157E+308 > 1.17549435E-38 2.2250738585072014E-308 > tally= 2.3058430049858406E+018 > 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 j and k and w > 13 175792128 -2147483648 13060694016. F wrong j and k and w > 14 1054752768 -2147483648 78364164096. F wrong j and k and w > STOP <ERROR>checkprod(3f):8*400000000=3200000000>2147483647
STANDARD
Fortran 95
SEE ALSO
DIGITS(3), EPSILON(3), EXPONENT(3), FRACTION(3), MAXEXPONENT(3), MINEXPONENT(3), NEAREST(3), PRECISION(3), RADIX(3), RANGE(3), RRSPACING(3), SCALE(3), SET_EXPONENT(3), SPACING(3), TINY(3)
Fortran intrinsic descriptions (license: MIT) @urbanjost
| Nemo Release 3.1 | huge (3fortran) | November 02, 2024 |
