epsilon(3I)

NAME
     EPSILON - Returns a positive number near 1 in the numeric model

SYNOPSIS
     EPSILON ([X=]x)

IMPLEMENTATION
     UNICOS, UNICOS/mk, and IRIX systems

STANDARDS
     Fortran 90

DESCRIPTION
     The EPSILON intrinsic function returns a positive model number that is
     almost negligible compared to unity in the model representing numbers
     of the same type and kind type parameter as the argument.  It accepts
     the following argument:

     x  Must be of type real.  It can be scalar or array valued.

     EPSILON is an inquiry function.  The name of this intrinsic cannot be
     passed as an argument.

RETURN VALUES
     The result type is a scalar of the same type and kind type parameter
     as x.  The result has the value
      (1-p)
     b      where b and p are as defined in the model for real numbers
     representing numbers of the same type and kind type parameter as x.
     For information on the real number model, see the MODELS(3I) man page.

EXAMPLES
     The following code fragment was run on several systems:

          REAL(KIND=4) r4
          REAL(KIND=8) r8
          REAL(KIND=16) r16
          REAL rd
          PRINT *,'EPSILON r4=',EPSILON(r4)
          PRINT *,'EPSILON r8=',EPSILON(r8)
          PRINT *,'EPSILON r16=',EPSILON(r16)
          PRINT *,'EPSILON rd=',EPSILON(rd)
          END

     The results of this test case on IRIX systems are as follows:

          EPSILON r4= 1.192092896E-7
          EPSILON r8= 2.22044604925031308E-16
          EPSILON r16= 1.23259516440783094595582588325435348E-32
          EPSILON rd= 1.192092896E-7

     The results of this test case on CRAY T90 systems that support IEEE
     floating-point arithmetic are as follows:

          EPSILON r4= 1.192092896E-7
          EPSILON r8= 2.22044604925031308E-16
          EPSILON r16= 1.92592994438723585305597794258492732E-34
          EPSILON rd= 2.22044604925031308E-16

     The results of this test case on UNICOS systems, except for CRAY T90
     systems that support IEEE floating-point arithmetic, are as follows:

          EPSILON r4= 1.192092895507812E-7
          EPSILON r8= 1.4210854715202E-14
          EPSILON r16= 5.04870979341447555463506281781E-29
          EPSILON rd= 1.4210854715202E-14

     The results of this test case on UNICOS/mk systems are as follows:

          EPSILON r4= 1.192092896E-7
          EPSILON r8= 2.22044604925031308E-16
          EPSILON r16= 2.22044604925031308E-16
          EPSILON rd= 2.22044604925031308E-16

SEE ALSO
     MODELS(3I)

     Intrinsic Procedures Reference Manual, publication SR-2138, for the
     printed version of this man page.