Generate next largest or smallest representable floating point number without bit twiddling
c++, floating-point
Solution
In C++11, you use `std::nextafter()`. Lacking that, on a C99 system, you use `nextafterf`, `nextafter`, or `nextafterl` from the C math library (for types `float`, `double`, and `long double`, respectively).
Problem
Given an arbitrary finite floating point number, is there a way to determine what the next representable floating point number? For example, given 1.0f, by definition the next largest representable number is 1.0f + std::numeric_limits<float>::epsilon(). Is there a way to synthesize an epsilon for any value - not just 1.0f - without resorting to bit twiddling and/or explicit knowledge of how the machine represents floating point values?