 Floating-point operations other than ordered comparisons normally propagate a quiet NaN ("qNaN").Most floating-point operations on a signaling NaN ("sNaN") signal the invalid operation exception; the default exception action is then the same as for qNaN operands and they produce a qNaN if producing a floating-point result.The propagation of quiet NaNs through arithmetic operations allows errors to be detected at the end of a sequence of operations without extensive testing during intermediate stages.