Return a copy of a, rounded to ‘decimals’ places.
When ‘decimals’ is negative, it specifies the number of positions to the left of the decimal point. The real and imaginary parts of complex numbers are rounded separately. Nothing is done if the array is not of float type and ‘decimals’ is greater than or equal to 0.
decimals : int
out : array_like
If out is given and does not have a mask attribute, the mask of a is lost!