Real*8 or Double Precision Must Contain an Exponent (31173)

The information in this article applies to:

Microsoft FORTRAN Compiler for MS-DOS 4.0
Microsoft FORTRAN Compiler for MS-DOS 4.01
Microsoft FORTRAN Compiler for MS-DOS 4.1
Microsoft FORTRAN Compiler for MS-DOS 5.0
Microsoft FORTRAN Compiler for MS-DOS 5.1
Microsoft FORTRAN PowerStation for MS-DOS 1.0
Microsoft FORTRAN PowerStation for MS-DOS 1.0a
Microsoft Fortran Powerstation 32 for Windows NT 1.0
Microsoft Fortran Powerstation 32 for Windows NT 4.0

This article was previously published under Q31173

SUMMARY

When using real*8 or double-precision variables, the FORTRAN manual says double-precision real constants have the same form as single-precision constants, except that the letter D is used for exponents instead of the letter E, and that an exponent part is mandatory.

To get 15 digits of precision into your real*8 variables, you must declare the constant with an exponent. If the exponent is omitted, the number is interpreted as a single-precision constant.

MORE INFORMATION

The following is a code example of the proper way to set a double-precision variable with the D:

            real*8 doub_real
   c      double precision doub_real
   c      either real*8 or double precision needs to use the D.


         doub_real = .55555555555555555555D0
         print '(f20.18)',doub_real
         end

Modification Type:	Major	Last Reviewed:	12/1/2003
Keywords:	kbLangFortran KB31173