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DrTip
Joined: 01 Aug 2006 Posts: 74 Location: Manchester
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Posted: Wed Nov 29, 2006 4:26 am Post subject: under flow with 3GB switch |
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Hi All
further to my previous question on debugging 3GB apps
we are finding a problem with underflows ( and presumably over flows)
here is a test program to illustate the issue
<snip>
!****Fails at i=87 on 64 bit machine
!*****but finishes on 32 bit machine
program testexponential
integer i
do i = 0,100
write (*,*) i,exp(-1.0*i)
end do
end program
</snip>
we are finding that when we run this on a standard pentium 4 XP machine with no 3GB switch turned on. At i = 88 the exponential returns 0.00000
and the loop finishes returning zeros
however on our Intel PWS390 running XP x64 the code just stops at i=87.
we are using the personal edition 4.9
is there some switch we must invoke to get the standard behaviour to happen again. we would very much not like to put lots of catches in legacy the code for this.
gievn the state of our code ie we would like the normal behaivou
Carl
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PaulLaidler Site Admin
Joined: 21 Feb 2005 Posts: 7928 Location: Salford, UK
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Posted: Thu Nov 30, 2006 2:05 am Post subject: under flow with 3GB switch |
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Carl
The Win64 underflow problem has already been fixed for FTN95 v5.0 (by default underflow nolonger raises an exception).
There should be no problem with overflow (i.e. by default overflow should raise an exception). |
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