RE: NEC-LIST:NEC 4.1 & g77

John,
Just searching around I found there is an "-e" flag option for the Absoft
g77 compiler. The effect of -e is to force results from math operations in
registers to have the floating point precision stated in the program. If
it is not specified, math is done at the normal precision of registers
unless the program code necessitates a store to memory - which I guess
without the "-e" option speeds up the processing time. Not sure if that
helps but you may want to try it.

v/r
Ken Carrigan

-----Original Message-----
From: John B. Wood [mailto:wood_at_itd.nrl.navy.mil]
Sent: Tuesday, July 09, 2002 8:31 AM
To: nec-list_at_gweep.ca
Subject: Re: NEC-LIST:NEC 4.1 & g77

Hello, all. After comparing the results of several simple antenna
models run on a Linux platform with the same models run on Windows
and HP-UX platforms I was ready to believe g77 was compiling NEC 4.1
into a reliable executable, Recently I tried the simple cone model:

CE cone - test - 3 MHz
GW 101 16 0 0 3 70.71 0 73.71 .012
GW 151 16 70.71 0 73.71 0 0 73.71 .012
GR 1 10
GW 1 2 0 0 0 0 0 3 .012
GE 1
GN 1
EX 0 1 1 0 100
LD 5 0 0 0 5.7E7
FR 0 0 0 0 3
RP 0 5 2 1001 90 0 -10 45
EN

I obtained the following driving point impedances (rounded to 3
significant figures) and maximum gains using this model:

Platform/Compiler Impedance Max Gain

Red Hat 7.1/g77 113 - j849 ohms +8,27 dBi

Win98/Compaq Visual Fortran 6.6 110 + j1.39 ohms +5.61 dBi

HP-UX 9.05/HP Fortran 110 + j1.39 ohms +5.61 dBi

As can be seen the reactive part of the feedpoint impedance using the
g77 compiler differs considerably from that obtained with the other
platforms. Again, scratching my head and wondering what's going on
here. Your comments are very much desired. Sincerely,

-- 
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