title: Same code using floats on two computers gives two different results
body: <p>I've got some image processing code in C++ which calculates gradients and finds straight lines in them with the hough transformation algorithm. The program does most of the calculations with floats. </p>
  
  <p>When I run this code on the same image on two different computers, one Pentium IV running latest Fedora, the other a Core i5 latest Ubuntu, both 32 bit, I get slightly different results. E.g. I have after some lengthy calculation 1.3456f for some variable on the one machine and 1.3457f on the other. Is this expected behavior or should I search for errors in my program? </p>
  
  <p>My first guess was, that I'm accessing some uninitialized or out-of-bounds memory but I did run the program through valgrind and it can't find any errors, also running multiple times on the same machine always gives the same results.</p>