math_fabs
double math_fabs(double a);
if (margin < 0 && math_fabs(margin) > EPSILON)
tb_delta = math_fabs(t_active_target - t_active_ref) * (hc_active_target + hc_blank_target_est1) / inter->t_line;
if (margin_target < 0 && math_fabs(margin_target) > EPSILON)