matlab 用num2str函数如何保留小数点后10位

% str = num2str(a, precision) converts the array A into a string
% representation str with maximum precision specified by precision.
% Argument precision specifies the number of digits the output string
% is to contain. The default is four.
>> num2str(C,12)
ans =
30.2359091167 30.2359091167