*To*: debian-mips@lists.debian.org*Cc*: debian-gcc@lists.debian.org*Subject*: SIN/COS broken in gfortran on mipsel? Test request*From*: "Kevin B. McCarty" <kmccarty@debian.org>*Date*: Mon, 17 Mar 2008 13:45:26 -0700*Message-id*: <[🔎] 47DED866.1030500@debian.org>

Dear list, I find it hard to believe, but it seems that the SIN() and COS() built-ins might be broken in gfortran on mipsel. See this build log for instance, search in it for the string "Testing Routine B101" and look at the table following that string: http://buildd.debian.org/fetch.cgi?&pkg=cernlib&ver=2006.dfsg.2-12&arch=mipsel&stamp=1205698992&file=log Judging by this build log, the SIN(x) and COS(x) functions on mipsel apparently return 0 and 1 respectively for x > 0 (and do not give the right values even for x = 0). Unfortunately, as far as I know there are no currently available mips/mipsel machines for developers to use, so I need to ask this list for help. I'm attaching a stand-alone version of this test as file "sincos.F". If someone running the latest Sid on a mipsel architecture wouldn't mind, please install the latest gfortran-4.3 package, run the following and see what you get: gfortran-4.3 -O2 sincos.F -o a.out ./a.out What you *should* get is something like the following: (obviously the exact errors will vary depending on floating point variations, but should be less than 1.0E-07) For A=I*PI/180: I X=SIN(A) Y=COS(A) ATG(X,Y) Error 0 0.0000000 1.0000000 0.0000000 0.0E+00 10 0.1736482 0.9848077 0.1745329 0.9E-07 20 0.3420202 0.9396926 0.3490659 0.0E+00 [snip] Largest Error for ATG was 0.9E-07 If the same bug as seen in the cernlib build log manifests itself, you will get something more like this: For A=I*PI/180: I X=SIN(A) Y=COS(A) ATG(X,Y) Error 0 0.9869969 0.1607389 1.4093571 0.0E+00 10 0.0000000 1.0000000 0.0000000 0.1E+01 20 0.0000000 1.0000000 0.0000000 0.1E+01 [snip] Largest Error for ATG was 0.1E+01 Please let me know (CC: to my email address) what is actually obtained on mipsel (and also on big-endian mips if possible). If you do get results significantly different from those shown above, please try compiling at lower optimization levels down to -O0 and see whether any of them give the correct results. Thank you and best regards, -- Kevin B. McCarty <kmccarty@gmail.com> WWW: http://www.starplot.org/ WWW: http://people.debian.org/~kmccarty/ GPG: public key ID 4F83C751

PROGRAM B101M C Specify the largest error allowed for a successful test PARAMETER ( TSTERR=1D-6 ) WRITE(6,'(/8X,''For A=I*PI/180:'')') WRITE(6,'(/5X,''I'',3X,''X=SIN(A)'',4X,''Y=COS(A)'',8X, + ''ATG(X,Y)'',4X,''Error'')') ER=0E0 ERMAX=0E0 PI = 3.14159 26535 89793D0 DO 1 I = 0,350,10 A=I*PI/180 X1=SIN(A) X2=COS(A) R1=ATG(X1,X2) IF (A .NE. 0.)ER=ABS((R1-A)/A) ERMAX=MAX(ERMAX,ER) WRITE(6,'(1X,I5,2F12.7,F15.7,E10.1)') I,X1,X2,R1,ER 1 CONTINUE WRITE(6,'(/7X,''Largest Error for ATG was'',E10.1)')ERMAX END FUNCTION ATG(X1,X2) PARAMETER (PI = 3.14159 26535 89793D0) ATG=ATAN2(X1,X2)+(PI-SIGN(PI,X1)) RETURN END

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**Follow-Ups**:**Re: SIN/COS broken in gfortran on mipsel? Test request***From:*"Kevin B. McCarty" <kmccarty@debian.org>

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