8.191 SELECTED_REAL_KIND — Choose real kind

Description:

SELECTED_REAL_KIND(P,R) returns the kind value of a real data type with decimal precision of at least P digits and exponent range greater at least R.

Standard:

Fortran 95 and later

Class:

Transformational function

Syntax:

RESULT = SELECTED_REAL_KIND([P, R])

Arguments:

P	(Optional) shall be a scalar and of type INTEGER.
R	(Optional) shall be a scalar and of type INTEGER.

At least one argument shall be present.

Return value:

SELECTED_REAL_KIND returns the value of the kind type parameter of a real data type with decimal precision of at least P digits and a decimal exponent range of at least R. If more than one real data type meet the criteria, the kind of the data type with the smallest decimal precision is returned. If no real data type matches the criteria, the result is

-1 if the processor does not support a real data type with a

precision greater than or equal to P

-2 if the processor does not support a real type with an exponent

range greater than or equal to R

-3 if neither is supported.

Example:

          program real_kinds
            integer,parameter :: p6 = selected_real_kind(6)
            integer,parameter :: p10r100 = selected_real_kind(10,100)
            integer,parameter :: r400 = selected_real_kind(r=400)
            real(kind=p6) :: x
            real(kind=p10r100) :: y
            real(kind=r400) :: z
          
            print *, precision(x), range(x)
            print *, precision(y), range(y)
            print *, precision(z), range(z)
          end program real_kinds