On Tue, 29 Apr 2008, John Maddock wrote:
Folks I'm looking for some good names for some functions I'm on the brink of adding to Boost.Math (all in namespace boost::math::):
T nextafter(T val, T dir) T next_greater(T val) T next_less(T val)
Given the first name is fixed, this is a reasonable family of names; though dropping the underscore would increase consistency. However, there is the ambiguity whether greater/less reference zero or infinity. nextpositive() and nextnegative() might be clearer. Why does this remind me of IEEE-754 rounding modes?
T edit_distance(T a, T b)
Returns the number of floating point representations between values a and b.
So the questions are: can you think of any better names, or are these OK?
And should edit_distance return a signed or absolute value?
I'm at a loss for a better name (representation_distance seems overly verbose but interval_size might be ok), but do have a couple questions about this function's behavior. Why is the return value templated? Shouldn't it be some fixed diff_t? I tentatively agree with the other comment that a signed distance is preferable to unsigned. Shouldn't this return the number of gaps, rather than the number of representations? Consider the following examples float x=1.0; float y=2.0; int d=edit_distance(x, y); float z=x; for(int i=0; i<d; i++) { z=next_greater(z); } // Does y==z? z=x; for(int i=0; i<d/2; i++) { z=next_greater(z); } // Does y==(x+z)/2, given the right rounding mode? Thanks, Daniel