Compiler question
Hi,
I compiled a program to perform relative rate tests on DNA sequences. It
is supposed to tell me, whether sets of sequences do differ in their
mutational rate or not.
This program is available for Mac PPC as well as binary and I did some
tests on the Mac and some on my Alpha. Besides the fact that the program
does crash a lot, I encountered a weird thing: Using the same datasets,
the two computers calculated different probability values. Now I am
confronted with the problem which computer to trust! The data were
supposed to be published!
I did now some testing with one dataset only.
The probability value that the tested DNA sequence differs from the
others on the Mac was calculated to be 1.12497e-07.
I tried then the compilates with both compilers available for Alpha:
gcc -o grrtree -O RRTree.c -lm
gcc -o grrtree -O RRTree.c -lffm -lm
gcc -o grrtree -O RRTree.c -lcpml -lffm -lm
gcc -o grrtree -O1 RRTree.c -lcpml -lffm -lm
gcc -o grrtree -O2 RRTree.c -lcpml -lffm -lm
gcc -o grrtree -O3 RRTree.c -lcpml -lffm -lm
gcc -o grrtree -O3 -mieee RRTree.c -lcpml -lffm -lm
gcc -o grrtree -O3 -mcpu=ev56 -Wa,-m21164a RRTree.c -lcpml -lffm -lm
ccc -o crrtree -O RRTree.c -lm
ccc -o crrtree -O RRTree.c -lffm -lm
ccc -o crrtree -O RRTree.c -lcpml -lffm -lm
ccc -o crrtree -O1 RRTree.c -lcpml -lffm -lm
ccc -o crrtree -O2 RRTree.c -lcpml -lffm -lm
ccc -o crrtree -O3 RRTree.c -lcpml -lffm -lm
ccc -o crrtree -O3 -ieee RRTree.c -lcpml -lffm -lm
In all the above cases the output was:
exact probability (P): 1e-07
As soon as -fast was included, the value changed:
ccc -o crrtree -O3 -fast RRTree.c -lcpml -lffm -lm
ccc -o crrtree -O3 -fast -ieee RRTree.c -lcpml -lffm -lm
exact probability (P): 6.17021e-07
The probability values of the first compiling attempts are slightly
lower than the one from the MacPPC. Can this be explained by 32 bit vs.
64 bit?
And about -fast: It looks to me like this option is introducing a bug.
What are the comments of the compiler and c-programming experts?
The relative rate tests without tree topology are not so time consuming,
I could skip -fast, but what about other compilations I do with it?
Regards,
Kerstin
--
kerstin.hoef-emden@uni-koeln.de
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