arm_sqrt_q31 return value for input value 0

[marcluque]

When working with the arm_sqrt_q31 function, I noticed that it returns ARM_MATH_ARGUMENT_ERROR for input 0. The documentation specifies that the allowed input range is [0, +1). I would expect 0 to return 0 and give ARM_MATH_SUCCESS instead, but it only does the former not the latter. The return value documentation seems to miss the "neutral" case since it specifies:

@return        execution status
                   - \ref ARM_MATH_SUCCESS        : input value is positive
                   - \ref ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0

Perhaps there's a wrong understanding of the code/documentation on my part.

[christophe0606]

@marcluque It is indeed a bug. A case is missing in the implementation for 0 argument. Same problem for the q15 version.

[christophe0606]

Corrected in commit 0d49aa6db8dabcdc7ee2f16879475a286ab6eb83

[marcluque]

Great, thank you very much! I'll close this issue then.