function fv=fitSingleZero(globalPar, cax)
    %par is a nfunc x npar matrix of coefficients
    %globalPar is a row vector of global coefficients
    %cax is a column vector of time instances
    %cay are the function values
    
    %oneVector=ones(1,size(cax,1));%column vector
    
    A=globalPar(1);
    tau=globalPar(2);
    alpha=globalPar(3);
    dt=globalPar(4);
    
    cax1=cax-dt;
    if tau==1/alpha
        fv=cax1.*exp(-cax1/tau);
    else
        fv=tau*(exp(-alpha*cax1)-exp(-cax1/tau))/(1-alpha*tau);
    end
    fv=fv*A;
    sel=cax1<0;
    fv(sel)=0;
    %fv=A*power(cax,alpha).*exp(-cax/tau)/power(tau,alpha);
   

end

%par=ones(2,