Gamma Function

         x                actual             gammln(x)
        1.00             0.000000             0.000000
        1.20            -0.085374            -0.085374
        1.40            -0.119613            -0.119613
        1.60            -0.112592            -0.112592
        1.80            -0.071084            -0.071084
        2.00             0.000000             0.000000
        0.20             1.524064             1.524064
        0.40             0.796678             0.796678
        0.60             0.398234             0.398234
        0.80             0.152060             0.152060
       10.00            12.801827            12.801827
       20.00            39.339884            39.339886
       30.00            71.257039            71.257042