Intel® Fortran Compiler Classic and Intel® Fortran Compiler Developer Guide and Reference
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real-size
Specifies the default KIND for real and complex declarations, constants, functions, and intrinsics.
Syntax
Linux:  |  
      -real-size size  |  
     
Windows:  |  
      /real-size:size  |  
     
Arguments
size  |  
      Is the size for real and complex declarations, constants, functions, and intrinsics. Possible values are: 32, 64, or 128.  |  
     
Default
real-size 32  |  
      Default real and complex declarations, constants, functions, and intrinsics are 4 bytes long (REAL(KIND=4) and COMPLEX(KIND=4)).  |  
     
Description
This option specifies the default size (in bits) for real and complex declarations, constants, functions, and intrinsics.
Option  |  
        Description  |  
       
|---|---|
real-size 32  |  
        Makes default real and complex declarations, constants, functions, and intrinsics 4 bytes long. REAL declarations are treated as single precision REAL (REAL(KIND=4)) and COMPLEX declarations are treated as COMPLEX (COMPLEX(KIND=4)). Real and complex constants of unspecified KIND are evaluated in single precision (KIND=4).  |  
       
real-size 64  |  
        Makes default real and complex declarations, constants, functions, and intrinsics 8 bytes long. REAL declarations are treated as DOUBLE PRECISION (REAL(KIND=8)) and COMPLEX declarations are treated as DOUBLE COMPLEX (COMPLEX(KIND=8)). Real and complex constants of unspecified KIND are evaluated in double precision (KIND=8).  |  
       
real-size 128  |  
        Makes default real and complex declarations, constants, functions, and intrinsics 16 bytes long. REAL declarations are treated as extended precision REAL (REAL(KIND=16)); COMPLEX and DOUBLE COMPLEX declarations are treated as extended precision COMPLEX (COMPLEX(KIND=16)). Real and complex constants of unspecified KIND are evaluated in extended precision (KIND=16).  |  
       
These compiler options can affect the result type of intrinsic procedures, such as CMPLX, FLOAT, REAL, SNGL, and AIMAG, which normally produce single-precision REAL or COMPLEX results. To prevent this effect, you must explicitly declare the kind type for arguments of such intrinsic procedures.
For example, if real-size 64 is specified, the CMPLX intrinsic will produce a result of type DOUBLE COMPLEX (COMPLEX(KIND=8)). To prevent this, you must explicitly declare any real argument to be REAL(KIND=4), and any complex argument to be COMPLEX(KIND=4).
IDE Equivalent
Visual Studio: Data > Default Real KIND
Alternate Options
real-size 32  |  
      Linux: -r4 Windows: /4R4  |  
     
real-size 64  |  
      Linux: -r8, -autodouble Windows: /4R8, /Qautodouble  |  
     
real-size 128  |  
      Linux: -r16 Windows: /4R16  |