xgboost-predictor/src/main/java/biz/k11i/xgboost/learner/ObjFunction.java
public static void useFastMathExp(boolean useJafama) {
        if (useJafama) {
            register("binary:logistic", new RegLossObjLogistic_Jafama());
            register("multi:softprob", new SoftmaxMultiClassObjProb_Jafama());

        } else {
            register("binary:logistic", new RegLossObjLogistic());
            register("multi:softprob", new SoftmaxMultiClassObjProb());
        }
    }
public static void useFastMathExp(boolean useJafama) {
        if (useJafama) {
            register("binary:logistic", new RegLossObjLogistic_Jafama());
            register("multi:softprob", new SoftmaxMultiClassObjProb_Jafama());

        } else {
            register("binary:logistic", new RegLossObjLogistic());
            register("multi:softprob", new SoftmaxMultiClassObjProb());
        }
    }
Uses Jafama's {@link FastMath#exp(double)} instead of {@link Math#exp(double)}.

@param useJafama {@code true} if you want to use Jafama's {@link FastMath#exp(double)},
or {@code false} if you don't want to use it but JDK's {@link Math#exp(double)}.