Undefined function 'rdivide' when doing Quantization DCT

I have problem when I do quantization with code below :

q_y ={16 11 10 16 24 40 51 61
    12 12 14 19 26 58 60 55
    14 13 16 24 40 57 69 56
    14 17 22 29 51 87 80 62
    18 22 37 56 68 109 103 77
    24 35 55 64 81 194 113 92
    49 64 78 87 103 121 120 101
    72 92 95 98 121 100 103 99};
fun2=@(block_struct) round(block_struct.data./q_y);
y = blockproc(b, [8 8], fun2);

it results this error :

Function BLOCKPROC encountered an error while evaluating the user supplied function
handle, FUN.
The cause of the error was:
Undefined function 'rdivide' for input arguments of type 'cell'.
Error in @(block_struct)round(block_struct.data./q_y)

why do I get this error?