#Java 7, <s>198</s> 182 bytes

    class M{public static void main(String[]a){System.out.print(Math.log(new Double(a[0])));}}//}};)))]0[a(elbuoD wen(pxe.htaM(tnirp.tuo.metsyS{)a][gnirtS(niam diov citats cilbup{M ssalc

AND

    class M{public static void main(String[]a){System.out.print(Math.exp(new Double(a[0])));}}//}};)))]0[a(elbuoD wen(gol.htaM(tnirp.tuo.metsyS{)a][gnirtS(niam diov citats cilbup{M ssalc

**Ungolfed:**

    class M{
        public static void main(String[]a){
            System.out.print(Math.log(new Double(a[0])));
        }
    }
    //}};)))]0[a(elbuoD wen(pxe.htaM(tnirp.tuo.metsyS{)a][gnirtS(niam diov citats cilbup{M ssalc

AND

    class M{
        public static void main(String[]a){
            System.out.print(Math.exp(new Double(a[0])));
        }
    }
    //}};)))]0[a(elbuoD wen(gol.htaM(tnirp.tuo.metsyS{)a][gnirtS(niam diov citats cilbup{M ssalc

----------

#Java 8, <s>192</s> 176 bytes

    class M{public static void main...

replaced with

    interface M{static void main...

----------

**Usage:**

    java -jar M.jar 5

Output:

    1.6094379124341003
    
    148.4131591025766