FIX: Complex Constant Folding Produces Incorrect Results

Last reviewed: September 16, 1997
Article ID: Q78927

5.10 | 5.10 MS-DOS | OS/2 kbtool kbfixlist kbbuglist

The information in this article applies to:

Microsoft FORTRAN for MS-DOS, version 5.1
Microsoft FORTRAN for OS/2, version 5.1

SYMPTOMS

The compiler attempts to calculate simple arithmetic expressions involving complex constants at the time of compilation. It produces incorrect results.

RESOLUTION

Assign complex constants to variables and use the complex variables in all arithmetic expressions.

STATUS

Microsoft has confirmed this to be a problem in the products listed above. This problem was corrected in FORTRAN PowerStation, version 1.0.

MORE INFORMATION

The following code can be used to reproduce the problem:

Sample code

      complex a,b,c

      b = (3,4)

      a = (3,4)**2.
      b = b**2

      c=(3,4)**2

c The above expression produces incorrect results because the c compiler "precalculates" the multiplication incorrectly. The c expression that has a decimal point on the 2 is not seen as a c multiplication so it is not calculated by the compiler. The run- c time correctly calculates complex expressions.

      print*, a
      print*, b
      print*, c  ! incorrect result
      end

Output from program:

      (-7.000000,24.000000)
      (-7.000000,24.000000)
   (-39.000000,-120.000000)  ! should also be (-7.000000,24.000000)

Additional reference words: 5.10 buglist5.10 fixlist1.00
KBCategory: kbtool kbfixlist kbbuglist
KBSubCategory: FLIss
Solution Type : kbfix

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: September 16, 1997
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.