Real*8 or Double Precision Must Contain an Exponent

• Microsoft FORTRAN for MS-DOS, versions 4.0, 4.01, 4.1, 5.0 and 5.1
• Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0 and 1.0a
• Microsoft FORTRAN PowerStation 32 for Windows NT, version 1.0 and 4.0

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