prtEvalPdAtPf   Returns the probability of false alarm at a desired
    probability of detection on the receiver operating curve.
 
    PD = prtEvalPdAtPf(prtClassifier, prtDataSet, pfDesired) returns the
    probabilty of detection PD.  prtDataSet must be a labeled, binary
    prtDataSetStandard object. prtClassifier must be a prtClass object.
    pfDesired is the desired probability of false alarm and must be between
    0 and 1.
 
    pfDesired = prtEvalPdAtPf(prtClassifier, prtDataSet, pfDesired, nFolds)
    returns the probabilty of false alarm pfDesired on the receiver
    operating curve with K-fold cross-validation. prtDataSet must be a
    labeled, binary prtDataSetStandard object. prtClassifier must be a
    prtClass object. pfDesired is the desired probability of detection and
    must be between 0 and 1. nFolds is the number of folds in the K-fold
    cross-validation.
 
    pfDesired = prtEvalPdAtPf(prtClassifier, prtDataSet, pfDesired,
    xValInds) same as above, but use crossValidation with specified indices
    instead of random folds.
 
    Example: 
    dataSet = prtDataGenSpiral; 
    classifier = prtClassDlrt;
    pf = prtEvalPdAtPf(classifier, dataSet,.01)