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     40 
     41 #include "precomp.hpp"
     42 
     43 namespace cv { namespace ml {
     44 
     45 ParamGrid::ParamGrid() { minVal = maxVal = 0.; logStep = 1; }
     46 ParamGrid::ParamGrid(double _minVal, double _maxVal, double _logStep)
     47 {
     48     minVal = std::min(_minVal, _maxVal);
     49     maxVal = std::max(_minVal, _maxVal);
     50     logStep = std::max(_logStep, 1.);
     51 }
     52 
     53 bool StatModel::empty() const { return !isTrained(); }
     54 
     55 int StatModel::getVarCount() const { return 0; }
     56 
     57 bool StatModel::train( const Ptr<TrainData>&, int )
     58 {
     59     CV_Error(CV_StsNotImplemented, "");
     60     return false;
     61 }
     62 
     63 bool StatModel::train( InputArray samples, int layout, InputArray responses )
     64 {
     65     return train(TrainData::create(samples, layout, responses));
     66 }
     67 
     68 float StatModel::calcError( const Ptr<TrainData>& data, bool testerr, OutputArray _resp ) const
     69 {
     70     Mat samples = data->getSamples();
     71     int layout = data->getLayout();
     72     Mat sidx = testerr ? data->getTestSampleIdx() : data->getTrainSampleIdx();
     73     const int* sidx_ptr = sidx.ptr<int>();
     74     int i, n = (int)sidx.total();
     75     bool isclassifier = isClassifier();
     76     Mat responses = data->getResponses();
     77 
     78     if( n == 0 )
     79         n = data->getNSamples();
     80 
     81     if( n == 0 )
     82         return -FLT_MAX;
     83 
     84     Mat resp;
     85     if( _resp.needed() )
     86         resp.create(n, 1, CV_32F);
     87 
     88     double err = 0;
     89     for( i = 0; i < n; i++ )
     90     {
     91         int si = sidx_ptr ? sidx_ptr[i] : i;
     92         Mat sample = layout == ROW_SAMPLE ? samples.row(si) : samples.col(si);
     93         float val = predict(sample);
     94         float val0 = responses.at<float>(si);
     95 
     96         if( isclassifier )
     97             err += fabs(val - val0) > FLT_EPSILON;
     98         else
     99             err += (val - val0)*(val - val0);
    100         if( !resp.empty() )
    101             resp.at<float>(i) = val;
    102         /*if( i < 100 )
    103         {
    104             printf("%d. ref %.1f vs pred %.1f\n", i, val0, val);
    105         }*/
    106     }
    107 
    108     if( _resp.needed() )
    109         resp.copyTo(_resp);
    110 
    111     return (float)(err / n * (isclassifier ? 100 : 1));
    112 }
    113 
    114 /* Calculates upper triangular matrix S, where A is a symmetrical matrix A=S'*S */
    115 static void Cholesky( const Mat& A, Mat& S )
    116 {
    117     CV_Assert(A.type() == CV_32F);
    118 
    119     int dim = A.rows;
    120     S.create(dim, dim, CV_32F);
    121 
    122     int i, j, k;
    123 
    124     for( i = 0; i < dim; i++ )
    125     {
    126         for( j = 0; j < i; j++ )
    127             S.at<float>(i,j) = 0.f;
    128 
    129         float sum = 0.f;
    130         for( k = 0; k < i; k++ )
    131         {
    132             float val = S.at<float>(k,i);
    133             sum += val*val;
    134         }
    135 
    136         S.at<float>(i,i) = std::sqrt(std::max(A.at<float>(i,i) - sum, 0.f));
    137         float ival = 1.f/S.at<float>(i, i);
    138 
    139         for( j = i + 1; j < dim; j++ )
    140         {
    141             sum = 0;
    142             for( k = 0; k < i; k++ )
    143                 sum += S.at<float>(k, i) * S.at<float>(k, j);
    144 
    145             S.at<float>(i, j) = (A.at<float>(i, j) - sum)*ival;
    146         }
    147     }
    148 }
    149 
    150 /* Generates <sample> from multivariate normal distribution, where <mean> - is an
    151    average row vector, <cov> - symmetric covariation matrix */
    152 void randMVNormal( InputArray _mean, InputArray _cov, int nsamples, OutputArray _samples )
    153 {
    154     Mat mean = _mean.getMat(), cov = _cov.getMat();
    155     int dim = (int)mean.total();
    156 
    157     _samples.create(nsamples, dim, CV_32F);
    158     Mat samples = _samples.getMat();
    159     randu(samples, 0., 1.);
    160 
    161     Mat utmat;
    162     Cholesky(cov, utmat);
    163     int flags = mean.cols == 1 ? 0 : GEMM_3_T;
    164 
    165     for( int i = 0; i < nsamples; i++ )
    166     {
    167         Mat sample = samples.row(i);
    168         gemm(sample, utmat, 1, mean, 1, sample, flags);
    169     }
    170 }
    171 
    172 }}
    173 
    174 /* End of file */
    175