Testing of mpfr maxnum and minnum functions
-------------------------------------------

    >>> import gmpy2
    >>> from gmpy2 import mpz, mpq, mpfr, maxnum, minnum
    >>> a = mpfr("12.34")
    >>> b = mpfr("45.67")
    >>> nan = mpfr("nan")
    >>> inf = mpfr("inf")
    >>> minf = mpfr("-inf")

Test maxnum
-----------

    >>> maxnum(a,b)
    mpfr('45.670000000000002')
    >>> maxnum(b,a)
    mpfr('45.670000000000002')
    >>> maxnum(a,-b)
    mpfr('12.34')
    >>> maxnum(a, 123456)
    mpfr('123456.0')
    >>> maxnum(12345678901234567890, a)
    mpfr('1.2345678901234567e+19')
    >>> maxnum(0, -1)
    mpfr('0.0')
    >>> maxnum(1, inf)
    mpfr('inf')
    >>> maxnum(1, -inf)
    mpfr('1.0')
    >>> maxnum(nan, a)
    mpfr('12.34')
    >>> maxnum(a, nan)
    mpfr('12.34')
    >>> maxnum(nan, inf)
    mpfr('inf')
    >>> maxnum(nan, -inf)
    mpfr('-inf')
    >>> maxnum(nan, nan)
    mpfr('nan')

Test minnum
-----------

    >>> minnum(a,b)
    mpfr('12.34')
    >>> minnum(b,a)
    mpfr('12.34')
    >>> minnum(1,inf)
    mpfr('1.0')
    >>> minnum(minf, a)
    mpfr('-inf')
    >>> minnum(nan, inf)
    mpfr('inf')
    >>> minnum(nan, nan)
    mpfr('nan')