docs: public static void permutationVector( DMatrixSparseCSC P , int[] vector) {
          if( P.numCols != P.numRows ) {
              throw new MatrixDimensionException("Expected a square matrix");
          } else if( P.nz_length != P.numCols ) {
              throw new IllegalArgumentException("Expected N non-zero elements in permutation matrix");
          } else if( vector.length < P.numCols ) {
              throw new IllegalArgumentException("vector is too short");
          }
  
          int M = P.numCols;
  
          for (int i = 0; i < M; i++) {
              if( P.col_idx[i+1] != i+1 )
                  throw new IllegalArgumentException("Unexpected number of elements in a column");
  
              vector[P.nz_rows[i]] = i;
          }
      }