@Override
 public String getLatexFormula() {
   Double minBiomassPercentage = (Double) getParameterValue(YIELD_PARAM_MIN_BIOMASS_PERCENTAGE);
   double percentage = MathUtils.round(minBiomassPercentage * 100, 2);
   return "$YIELD = max (\\text{"
       + getParameterValue(YIELD_PARAM_PRODUCT)
       + "}); biomass \\ge "
       + percentage
       + "\\% wt$";
 }
 public String toString() {
   Double minBiomassPercentage = (Double) getParameterValue(YIELD_PARAM_MIN_BIOMASS_PERCENTAGE);
   String productID = (String) getParameterValue(YIELD_PARAM_PRODUCT);
   double percentage = MathUtils.round(minBiomassPercentage * 100, 2);
   return "YIELD> percentage=" + percentage + ";target=" + productID;
 }