Python replaces Matlab (at least for me)

The emergence of Matlab during the last decade of the 20th century highly changed the way we develop, implement and test numerical algorithms: In the old days we used C, sometimes  Fortran or C++.  We spent a lot of  time in writing low-level functions and debugging memory leaks. Matlab helped us a lot. Debugging numerical algorithms is hard, because dumping a 100 times 100 matrix will not really give you the information you are looking for. Therefore visualization of data is very important for developing numerical code  efficiently. Gnuplot helped us, but Matlab provided nice interactive 3d graphics and a tight integration. We naturally moved away from  cumbersome ‘ waterfall method ‘ alike planing and coding  to some agile ‘lets try things out - we only need a few minutes’ . Matlab gave us the ability to play with  data and algorithms. But Matlab is expensive if you can not apply for an academic license, it is closed source and  last but...