It's common everywhere except in ivory towers. Mathematical journals (english ones, at least) and the like use log to mean the natural log, because there's no n

It's common everywhere except in ivory towers. Mathematical journals (english ones, at least) and the like use log to mean the natural log, because there's no need to use log_10 in any advanced/abstract system. (This is because 10 stops being a number of any import past being able to do arithmetic in your head; 10 is only special because we have that many fingers.) The sciences have a definite use for log_10, since the metric system is based around powers of 10. A mathematician might argue that e.g. a log-lin graph would be just as useful with log_e as log_10, but then you lose the nice demarcations. It all depends who you're talking to and how they're using it. As a professional mathematician, the author sees little need for log to mean anything other than the natural log. As a professional educator, I disagree. Clearly his readers are confused by the ambiguity of "log". He has a few options: do nothing and accept that inexperienced but curious mathematicians will be confused, use "ln" in place of "log" when writing wider interest instead of journal articles, or write a blog post complaining about it and hope the world will change to suit him. edit: Although we pronounced ln "len" or "lin" instead of "lawn"