https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953861#M20273 Actually, the error is coming during the linking, not the execution. The line you show is of the reference to CDAT, not the declaration.<BR /><BR />Since you have the sources - find routine CDAT and reply here with the SUBROUTINE or FUNCTION statement, and all the type declarations of its arguments. Do the same with the call to CDAT (the call statement and the types of its arguments). My guess is that you have a type mismatch.<BR /><BR />Steve Thu, 31 May 2001 09:19:06 GMT Steven_L_Intel1 2001-05-31T09:19:06Z https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953858#M20270 I'm working on an old code and trying to modify it.Original code is compiled with NPD Fortran compiler (which I've not heard before) and now I've the very classical error for you "error LNK2001: unresolved external symbol _CDAT@20".Is the problem due to the mixed version of libraries?If yes, how can I find the the right lib file? Wed, 30 May 2001 10:56:54 GMT https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953858#M20270 Intel_C_Intel 2001-05-30T10:56:54Z https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953859#M20271 It probably will not work to link CVF code against libraries compiled by the NPD compiler. Do you have all the sources?<BR /><BR />If the NPD code is link-compatible with CVF, you probably still have to deal with differences in naming and calling conventions. In a Fortran Command Prompt window, do a:<BR /><BR />dumpbin -symbols xxx.obj &gt; dump.txt<BR /><BR />on the object (or .lib) Then open dump.txt in NOTEPAD and look for CDAT to see how it appears. Look for lines that resemble this:<BR /><BR /><FONT size="+1"><PRE> 00C 00000000 SECT1 notype () External | _TEST@0 </PRE></FONT><BR /><BR />You want to see how the name CDAT appears here - is it _cdat, _CDAT, or something else?<BR /><BR />Steve Wed, 30 May 2001 22:29:50 GMT https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953859#M20271 Steven_L_Intel1 2001-05-30T22:29:50Z https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953860#M20272 Yes I have all the source codes.When I'm compiling these codes there is no error.The error comes during the execution of the program. <BR />I did exactly what you said (In Fortran Command Prompt) and I'm copying the line including CDAT: <BR /> <BR />019 00000000 UNDEF notype () External | _CDAT@20 <BR /> <BR />nc Thu, 31 May 2001 09:08:31 GMT https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953860#M20272 Intel_C_Intel 2001-05-31T09:08:31Z https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953861#M20273 Actually, the error is coming during the linking, not the execution. The line you show is of the reference to CDAT, not the declaration.<BR /><BR />Since you have the sources - find routine CDAT and reply here with the SUBROUTINE or FUNCTION statement, and all the type declarations of its arguments. Do the same with the call to CDAT (the call statement and the types of its arguments). My guess is that you have a type mismatch.<BR /><BR />Steve Thu, 31 May 2001 09:19:06 GMT https://community.intel.com/t5/Software-Archive/Compatibility-with-NPD-Fortran-compiler/m-p/953861#M20273 Steven_L_Intel1 2001-05-31T09:19:06Z