I need to do fitting with a integral function and a data experimt

function f= integral(par,tdata);

tmax=length(tdata);

a=par(1);

for i=1:tmax;
    tk=tdata(i);

      f_s=@(s)(a.*s.^2);

f(i)=quadv(@(m)f_s(tk),0,1);
end