The Porting of Mainframe-Dependent Antenna Modeling Program (NEC-3) to a 32-Bit Personal Computer

The purpose of this thesis was to demonstrate the feasibility of porting a large mainframe-dependent scientific FORTRAN program, specifically the Numerical Electromagnetics Code NEC-3 to a 32-bit personal computer. Two systems, an AST Premium 38633 with both Intel 80387 and Weitek w3167 math co- processors and a Definicon DSI-780 using a Motorola 68020 CPU and 68881 math co- processor, were used with several 32-bit FORTRAN 77 compilers. Results show that when Nec-3 was promoted to full double precision, complete accuracy was maintained while suffering only a 12 increase in execution time over single precision. Testing also revealed that the double precision Weitek version is 30 faster than the 80387 version. Some small inaccuracies remain however, the same results were obtained by both the Naval Postgraduate School mainframes new IBM VS2 FORTRAN 77 compiler and the personal computer FORTRAN 77 compilers. This indicates that the bug is in the NEC-3 code, vice being hardware or FORTRAN 77 compiler problem.