F isint(f)
   R Complex(f).imag == 0 & fract(Complex(f).real) == 0

print([Complex(1.0), 2, (3.0 + 0.0i), 4.1, (3 + 4i), (5.6 + 0i)].map(f -> isint(f)))
print(isint(25.000000))
print(isint(24.999999))
print(isint(25.000100))
print(isint(-5e-2))
print(isint(Float.infinity))
print(isint(5.0 + 0.0i))
print(isint(5 - 5i))