how can I assign values to time series data

I have time series data which contains 2000 data points which is given as , S(t)= 2.5e-02t^6-5.8e-03t^5 . The function has peaks and lowest points . I want to assign a certain property to S(t) which starts from each peak of s(t) . The proposed property which I intend to assign has 26 elements , j(t). This value is recurring starting from each peak of s(t).

I repmatted the j(t) to s(t) but the points doesn't start from each peak

here is the script I tried to work upon

    d= repmat(j(t), [1 77]); %%%2000/26 ¬=77
    d=d(1:2000,1);

but the the peak in d and s(t) doesn't coincide Can anyone show me how to do this? am new to matlab? thanks for your help.