code: public static LinearSolverDense<DMatrixRMaj> general(int numRows , int numCols ) {
          if( numRows == numCols )
              return linear(numRows);
          else
              return leastSquares(numRows,numCols);
      }
docs: Creates a general purpose solver.  Use this if you are not sure what you need.
  
  @param numRows The number of rows that the decomposition is optimized for.
  @param numCols The number of columns that the decomposition is optimized for.