Riddle me this Batman: how much precision are these calculations evaluated at? If you answered ‘double’ and ‘float’ then you score one point for youthful idealism, but zero points for correctness. The correct answer, for zero-idealism points and forty two … Continue reading
After a recent post on float precision there was some debate about round-tripping of floats. My claim was that if you print a float with printf(“%1.8e”, f); and then scan it back in then you are guaranteed to get back … Continue reading
How much precision does a float have? It depends on the float, and it depends on what you mean by precision. Typical reasonable answers range from 6-9 decimal digits, but it turns out that you can make a case for … Continue reading
This post is a more carefully thought out and peer reviewed version of a floating-point comparison article I wrote many years ago. This one gives solid advice and some surprising observations about the tricky subject of comparing floating-point numbers. We’ve … Continue reading
I promised in my last post to show an example of the importance of knowing how much precision a float has at a particular value. Here goes. As a general rule this type of data should never be stored in … Continue reading
This is a special bonus extra post in my floating-point series, ranting about an issue that has been a problem for years. Some debuggers don’t display floats with enough precision.
Type Punning is Not a Joke I left the last post with a promise to share an interesting property of the IEEE float format. There are several equivalent ways of stating this property, and here are two of them.