Data types of arrays in a function

Hey,

I am trying to create a function that takes an array as an input arg and returns another array as output arg which should be if all elements of the input array are within the range of int8 is an int8, otherwise, it is the same type as the input array...The function is called as B=safe_int8(A).

I am using the following loop....

B=zeros(size(A)); % Pre-allocation since B changes size
for ii=1:size(A,1)
    for jj=1:size(A,2)
        if -128<A(ii,jj)&& A(ii,jj)<127
            A=int8(A);
            B=A;
        else
            B=(A);
        end
    end
end

Running it yields for instance

>> A=[1 0 3;4 5 6];
>> B=safe_int8(A)
B =
  2×3 int8 matrix
   1   0   3
   4   5   6
>> A=[1 0 345;4 5 6];
>> B=safe_int8(A)
B =
  2×3 int8 matrix
     1     0   127
     4     5     6
>> A=[1 1.05 3;4 5 6];
>> B=safe_int8(A)
B =
  2×3 int8 matrix
   1   1   3
   4   5   6

Of course, the first trial gives the right answer; but the second and third which should give the class for B as double are instead returning it as an int8...How do i correct this?

Answer 1

[madhan ravi]

        if all((-128<=A)& (A<=127))
            A=int8(A);
            B=A;
        else
            B=(A);
        end

Loops are not necessary here.

Answer 2

[Stephen23]

B = int8(A);
if any(B(:)~=A(:))
    B = A;
end

Note that this is a more versatile approach because it does not use hard-coded values, i.e. you can trivially change only the type conversion function and it will work. The type conversion function could even be a function handle.

[Samuel Katongole]

Thanks bro