Herbie: Find and fix floating-point accuracy problems

Hey! Some people in my lab work on that! I also did some work on analyzing floating point exceptions, so I learned a bit about this stuff. AMA, and I’ll do my best to answer. :) (For clarification, I work at the University of Utah, so Pavel is the head honcho over Herbie here.)

They made a related project - http://herbgrind.ucsd.edu/ - a tool that can automatically find floating point issues in real programs. You can also annotate the region you're interested in with herbgrind on/off controls. Unfortunately - once you know you have a floating point problem, tracking it down and fixing it may be easy. Not realising it, you won't use these tools and the program will do the wrong thing :)

Herbie - the tool which exists today - is excellent, but the perhaps more significant insight is that this could and should in principle be baked into compilers. That is, a future language should let you say here's a real expression, and I want you to give me an approximation in my 64-bit floating point representation, and here's the parameters for accuracy and performance. What do those parameters look like? Herbie's existing UI might help us somewhat but it's definitely…