function compositionDisturbance(x, Compfrac, stp_z)

    for i = 1:4
        if i ~= x 
            Compfrac_d(i) = Compfrac(i) - stp_z * Compfrac(i) / (sum(Compfrac) - Compfrac(x));
        else
            Compfrac_d(i) = Compfrac(i) + stp_z;
        end
    end
    
       
    fid = fopen('compChange.scp', 'r+');
    fseek(fid, 179, 'bof');
    fprintf(fid, '%1.7e',Compfrac_d(1));
    fclose(fid);

    fid = fopen('compChange.scp', 'r+');
    fseek(fid, 332, 'bof');
    fprintf(fid, '%1.7e',Compfrac_d(2));
    fclose(fid);

    fid = fopen('compChange.scp', 'r+');
    fseek(fid, 485, 'bof');
    fprintf(fid, '%1.7e',Compfrac_d(3));
    fclose(fid);

    fid = fopen('compChange.scp', 'r+');
    fseek(fid, 638, 'bof');
    fprintf(fid, '%1.7e',Compfrac_d(4));
    fclose(fid);

    