1D dct equation implementation

i have written a code to implent 1D dct formula. but the results are not matching with result of inbuilt function 'dct' for the same input data. can anyone help me to solve the problem.here is the code

clc;
pi=3.14;
arr=[8 8 8 8 8 8 8 8];

for k=1:8

      temp=0;
      DCT(k)=0;
      for i=1:8
          if k==1
              c=1/sqrt(8);
          else 
              c=sqrt(2/8);

              temp=temp+(arr(i)*cos((2*i+1)*k*(pi)/16));

          end
      end
      DCT(k)=c*temp;
      display(DCT(k))
  end