In linux using pthreads When I call a whatever usual function like for instance: thread 1 a=div(b,c).rem thread 2 x=div(y,z).rem so I call the same function on different (not shared) data Can I be sure that the two function calls by the two threads do not share any (internal) data (may be registers or global-library-shared) and so have no side unpredicted effect?? The same question holds for usual functions like sin() exp() pow() rand() nanosleep() etc.

astella, I get all sorts of results when I search for this, so not sure how helpful, if at all, any of these links are. They discuss things like "thread safety" and "mutexes": http://www-128.ibm.com/developerworks/library/l-pthred.html http://www.yolinux.com/TUTORIALS/LinuxTutorialPosixThreads.html http://students.cs.byu.edu/~cs460ta/cs460/labs/pthreads.html Cheers!