The fdim, fdimf, and fdiml functions return the positive difference between x and y. That is, if x- y is positive, then x- y is returned. If either x or y is an NaN, then an NaN is returned. Otherwise, the result is +0.0.
Overflow or underflow may occur iff the exact result is not representable in the return type. No other exceptions are raised.
fabs(3), fmax(3), fmin(3), math(3)