docs: public static DMatrixRMaj minCols(DMatrixSparseCSC input , @Nullable DMatrixRMaj output ) {
          if( output == null ) {
              output = new DMatrixRMaj(1,input.numCols);
          } else {
              output.reshape(1,input.numCols);
          }
  
          for (int col = 0; col < input.numCols; col++) {
              int idx0 = input.col_idx[col];
              int idx1 = input.col_idx[col + 1];
  
              // take in account the zeros
              double min = idx1-idx0 == input.numRows ? Double.MAX_VALUE : 0;
              for (int i = idx0; i < idx1; i++) {
                  double v = input.nz_values[i];
                  if( min > v ) {
                      min = v;
                  }
              }
              output.data[col] = min;
          }
  
          return output;
      }