http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53509
Bug #: 53509 Summary: exp and log function give unexpected results when called with numbers as arguments Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran AssignedTo: unassig...@gcc.gnu.org ReportedBy: f.ba...@gmail.com Created attachment 27513 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27513 test script for testing log and exp function I noticed that the exp and log function in gfortran 4.7.0 and 4.5.3 on OSX Lion/macports give unexpected results. When I call exp(1.0) I get 2.76.. and when I call log(2.71...) I get 1.34... $ gfortran-mp-4.7 ./test.f90 && ./a.out 2.76998615 1.34896958 I tried debugging the program, when in the debugger calling log(2.71..) results in the correct value. Another way to get the correct answer is to store the 2.71 in a variable and calling log on that. I also tried with other real types and they all give different but incorrect answers. Please find attached a test program that reproduces the error on OSX Lion. Cheers, Fedor See also: http://trac.macports.org/ticket/34535 http://stackoverflow.com/questions/10673701/can-i-call-the-fortran-log-function-with-a-number