spectrum sensing via wavelet modulus maxima

i have coding to get spectrum sensing via wavelet modulus maxima. but i have problem where the error : Arrays have incompatible sizes for this operation. after i add first_order

j = [1 2 3 4];

s = 2.^j;

cwt = conv2 (y_amp_transpose, teta_f_transpose);

d1 = diff(cwt,1);

first_order = s.*(d1);