package osu.crowd_ml;

/*
Copyright 2016 Crowd-ML team


Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License
*/

public class Laplace implements Distribution{

    public double noise(double mu, double noiseScale){
        double rng = Math.random();
        int sgn;
        if((rng-0.5)<0)
            sgn = -1;
        else
            sgn = 1;
        b = noiseScale / sqrt(2)
        double noise = mu - b*sgn*Math.log(1-2*Math.abs(rng-0.5)); //inverse cumulative laplace Distribution
        return noise;
    }
}

package osu.crowd_ml;

/*
Copyright 2016 Crowd-ML team
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License
*/

public class Laplace implements Distribution{

    public double noise(double mu, double noiseScale){
        double rng = Math.random();
        int sgn;
        if((rng-0.5)<0)
            sgn = -1;
        else
            sgn = 1;
        double b = noiseScale / Math.sqrt(2);
        double noise = mu - noiseScale*sgn*Math.log(1-2*Math.abs(rng-0.5)); //inverse cumulative laplace Distribution
        return noise;
    }
}

Update Laplace.java