EPSILON(3I) Last changed: 1-6-98
EPSILON - Returns a positive number near 1 in the numeric model
EPSILON ([X=]x)
UNICOS, UNICOS/mk, and IRIX systems
Fortran 90
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.
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.
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
MODELS(3I)
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
EPSILON(3I) Last changed: 1-6-98
EPSILON - Returns a positive number near 1 in the numeric model
EPSILON ([X=]x)
UNICOS, UNICOS/mk, and IRIX systems
Fortran 90
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.
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.
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
MODELS(3I)
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
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