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EPSILON(3I)					       Last changed: 1-6-98

NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

     EPSILON ([X=]x)

IMPLEMENTATION    [Toc]    [Back]

     UNICOS, UNICOS/mk,	and IRIX systems

STANDARDS    [Toc]    [Back]

     Fortran 90

DESCRIPTION    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

      
      
     MODELS(3I)

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

EPSILON(3I)					       Last changed: 1-6-98

NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

     EPSILON ([X=]x)

IMPLEMENTATION    [Toc]    [Back]

     UNICOS, UNICOS/mk,	and IRIX systems

STANDARDS    [Toc]    [Back]

     Fortran 90

DESCRIPTION    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

      
      
     MODELS(3I)

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

[ Back ]
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