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From: jeyadev@WRC.XEROX.COM (Surendar Jeyadev)
Newsgroups: comp.lang.fortran,alt.sys.sun
Subject: Sun Fortran Unformatted Write
Message-ID: <769@rocksanne.WRC.XEROX.COM>
Date: 3 Apr 91 23:58:15 GMT
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Reply-To: jeyadev@WRC.XEROX.COM (Surendar Jeyadev)
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Sometime ago there was a spate of articles about problems connected
with the unformatted write statement in Sun Fortran 1.3.1. I did not
see what the conclusion was, but we seem to be running into a similar
problem. The program in question has the following statements:

......
imax = 56
jmax = 22
kmax = 17
 
write(3) (((array(i,j,k), k=1,kmax), j=1,jmax), i=1,imax)
.......
 
While the version 1.2 did not seem to mind, version 1.3.1 declares
a segmentation fault and quits. Using dbx I got
 
signal SEGV (no mapping at the fault address) in w4cp at 0xf76f0724
w4cp+8: ld  [%o0 + %o1],  %o4
 
but I do not know what to do with this!
 
The user of this program used to run it on a VAX and the write 
statement was tailored to take into account the fact that the maximum
number of records that could be written is 8191. After playing around
a bit with the values of imax, jmax and kmax, I found that the program
works fine for small values of the 3 numbers, but crashes when their
product reaches a critical value.

A simple program that writes out a vector with

.......
lmax = <some integer less than declared size of a>
write(3) (a(i), l=1,lmax)
.......

reveals that the program crashes when lmax reaches 2046. 

Now the question. Is this well known? I cannot find anything about this
in the manuals (such as they are). I understand that the workaround is
easy, but, has this been observed/documented? And, since the user 
depends heavily on unformatted writes, are there any other limitations
for unformatted writes?

Thanks

--
Surendar Jeyadev     Internet: jeyadev.wbst128@xerox.com

Most books say that the sun is a star. But, somehow, it knows how to
change back to a sun in the morning.  (5th grader)