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user2006189
user2006189

Reputation: 143

Exponential function giving different results in Java and Matlab

I have an n by 2 array 'ppi' having integer values(with duplicate), a second array n by 1 'gid' containing unique integer values from 'ppi' and a third array 'X0' with 0 and 1 values. Below is a MATLAB code which I want to implement in Java-

MATLAB version-

    gamma0 = 10; gamma1 = 10; beta = 20;
    delta = 0;weight=10;
    for i=1:length(gid)
    gconn = union(ppi(find(ppi(:,1)==gid(i)),2), ppi(find(ppi(:,2)==gid(i)),1));
    [a,b] = intersect(gid, gconn);
    u1 = (X0(i)*weight + sum(X0(b)==1))/(weight+length(gconn)); 
    u0 = ((1-X0(i))*weight + sum(X0(b)==0))/(weight+length(gconn));
    mrfpdf(i) = exp((1-X0(i))*(gamma0-beta*u1)+X0(i)*(gamma1-beta*u0))/(exp(gamma0-           beta*u1)+exp(gamma1-beta*u0));
    end

Java code for the same implementation

    double[] mrfpdf = new double[X0.length];
    Integer[] X = new Integer[X0.length];

    // find out unique class labels in ppi
    Set<Double> gid_set = new LinkedHashSet<Double>();
    for (int i = 0; i < ppi.length; i++) {
    for (int j = 0; j < ppi[0].length; j++) {
    gid_set.add(ppi[i][j]);
    }
    }
    System.out.println("unique gid_set: " + gid_set);
    Double[] gid = gid_set.toArray(new Double[gid_set.size()]);
    Arrays.sort(gid);

    int gamma0 = 10, gamma1 = 10, beta = 20, delta = 0;weight=10;
    for (int i = 0; i < gid.length; i++) {

    Set<Double> ppi1 = new HashSet<Double>();
    Set<Double> ppi2 = new HashSet<Double>();
    for (int k = 0; k < ppi.length; k++) {
    if (ppi[k][0] == gid[i])
    ppi1.add(ppi[k][1]);

    if (ppi[k][1] == gid[i])
    ppi2.add(ppi[k][0]);

    }

    Set<Double> gconn = new HashSet<Double>(ppi1);
    gconn.addAll(ppi2);
    Set<Double> a = new HashSet<Double>(gid_set);
    a.retainAll(gconn);
    java.util.List<Double> buff = new LinkedList<Double>(gid_set);
    int[] b = new int[a.size()];// get index of intersection elements in this array
    int x = 0;
    for (double j : a) {
    for (int c = 0; c < gid.length; c++) {
    if (j == gid[c]) {
    b[x] = c;
    x++;
    }
    }
    }
    java.util.List<Double> X0_list = new ArrayList<Double>();
    for (double z : X0) {
    X0_list.add(z);
    }
    int sum1 = 0;
    for (int y : b) {
    if (X0_list.get(y) == 1)
    sum1++;
    }
    int sum2 = 0;
    for (int y : b) {
    if (X0_list.get(y) == 0)
    sum2++;
    }
    u1 = (int) ((X0[i] * weight + sum1) / (weight + gconn.size()));
    u0 = (int) (((1 - X0[i]) * weight + sum2) / (weight + gconn.size()));
    mrfpdf[i] = (Math.exp((1 - X0[i]) * (gamma0 - beta * u1) + X0[i]* (gamma1 - beta * u0)) / (Math.exp(gamma0 - beta * u1) + Math.exp(gamma1 - beta * u0)));

    }// end for(int i : gid)
    }

Can someone please tell me why the values in mrfpdf array is different in Java and Matlab code? Java code results in 0.99 and 0.5 values only whereas Matlab does not have any 0.5 value

Thanks

Upvotes: 0

Views: 377

Answers (1)

Daniel
Daniel

Reputation: 36710

Your matlab-code uses doubles while java-code uses integers (e.g. u0 and u1)

Upvotes: 1

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