prtScoreAuc Calculates the area under the ROC curve
 
    AUC  = prtScoreAuc(GUESS, TRUTH) returns the
    percent of correct guesses in GUESS as compared to the truth in TRUTH.
    GUESS and TRUTH should both be Nx1 vectors. The elements of both
    TRUTH and GUESS should be binary or interger class labels.
 
 
    Example:
    TestDataSet = prtDataGenUnimodal;       % Create some test and
    TrainingDataSet = prtDataGenUnimodal;   % training data
    classifier = prtClassMap;               % Create a classifier
    classifier = classifier.train(TrainingDataSet);    % Train
    classified = run(classifier, TestDataSet);         % Test
    auc = prtScoreAuc(classified,TestDataSet)