o 8Va'@sddlmZddlmZmZddlmZm Z ddl m Z  dddZ  dd d Z e fd d Ze d d fddZe d fddZe d ddfddZdS)) FunctionType)simplify dotprodsimp)_get_intermediate_simp_iszero)_find_reasonable_pivotTc s8fdd} fdd} fdd} ttd\} } g}g}| kr| |krt| | | d||\}}}}|D]\}}|| 7}||| <q<|durV| d 7} q"|| |d kro| | || || || f|d ur| | }}|||<t||d |d D] }|||<q|}t|D]$}|| krq|d ur|| krq|| }||rq| |||| q| d 7} | kr| |ks*|d ur|d urt|D]1\}}||}|||<t||d |d D] }|||<qqt|t|fS) aRow reduce a flat list representation of a matrix and return a tuple (rref_matrix, pivot_cols, swaps) where ``rref_matrix`` is a flat list, ``pivot_cols`` are the pivot columns and ``swaps`` are any row swaps that were used in the process of row reduction. Parameters ========== mat : list list of matrix elements, must be ``rows`` * ``cols`` in length rows, cols : integer number of rows and columns in flat list representation one : SymPy object represents the value one, from ``Matrix.one`` iszerofunc : determines if an entry can be used as a pivot simpfunc : used to simplify elements and test if they are zero if ``iszerofunc`` returns `None` normalize_last : indicates where all row reduction should happen in a fraction-free manner and then the rows are normalized (so that the pivots are 1), or whether rows should be normalized along the way (like the naive row reduction algorithm) normalize : whether pivot rows should be normalized so that the pivot value is 1 zero_above : whether entries above the pivot should be zeroed. If ``zero_above=False``, an echelon matrix will be returned. cs|dSNicolsmatr ;/usr/lib/python3/dist-packages/sympy/matrices/reductions.pyget_col/sz!_row_reduce_list..get_colcs^||d||d||d<||d<dS)Nrr )r jr r rrow_swap2s.0z"_row_reduce_list..row_swapcsP||}t||dD]}||||||<qdS)z,Does the row op row[i] = a*row[i] - b*row[j]rN)range)ar brqprZisimprr r cross_cancel6s &z&_row_reduce_list..cross_cancelrrNrrFT)r _dotprodsimprappendr enumeratetuple)rrowsrone iszerofuncsimpfuncnormalize_last normalize zero_aboverrrZpiv_rowZpiv_col pivot_colsswapsZ pivot_offsetZ pivot_valZassumed_nonzeroZnewly_determinedoffsetvalr rrrowZpiv_iZpiv_jr rr_row_reduce_list s`%   " /"r,c CsBtt||j|j|j|||||d \}}}||j|j|||fS)Nr$r%r&)r,listr rr!Z_new) Mr"r#r$r%r&rr'r(r r r _row_reduce|s  r0cs|jdks |jdkr dStfdd|dddfD}|dr2|o1t|ddddfS|o@t|ddddfS)zReturns `True` if the matrix is in echelon form. That is, all rows of zeros are at the bottom, and below each leading non-zero in a row are exclusively zeros.rTc3s|]}|VqdSr r ).0tr"r r sz_is_echelon..rNr)r rall _is_echelon)r/r"Z zeros_belowr r3rr6s " r6FcCs<t|tr|nt}t|||dddd\}}}|r||fS|S)anReturns a matrix row-equivalent to ``M`` that is in echelon form. Note that echelon form of a matrix is *not* unique, however, properties like the row space and the null space are preserved. Examples ======== >>> from sympy import Matrix >>> M = Matrix([[1, 2], [3, 4]]) >>> M.echelon_form() Matrix([ [1, 2], [0, -2]]) TFr- isinstancer _simplifyr0)r/r"rZ with_pivotsr#rpivots_r r r _echelon_forms r<c sdd}t|tr |nt}|jdks|jdkrdS|jdks#|jdkr2fdd|D}d|vr2dS|jdkre|jdkrefd d|D}d|vrOd |vrOdS|}|r]d|vr]dS|duredS||d \}}t||d ddd \}} }t| S)zReturns the rank of a matrix. Examples ======== >>> from sympy import Matrix >>> from sympy.abc import x >>> m = Matrix([[1, 2], [x, 1 - 1/x]]) >>> m.rank() 2 >>> n = Matrix(3, 3, range(1, 10)) >>> n.rank() 2 csJfddfddtjD}ddt|D}j|dd|fS)aPermute columns with complicated elements as far right as they can go. Since the ``sympy`` row reduction algorithms start on the left, having complexity right-shifted speeds things up. Returns a tuple (mat, perm) where perm is a permutation of the columns to perform to shift the complex columns right, and mat is the permuted matrix.cs"tfdddd|fDS)Nc3s$|] }|dur dndVqdS)Nrrr )r1er3r rr4s"zO_rank.._permute_complexity_right..complexity..)sumr )r/r"r r complexitys"z<_rank.._permute_complexity_right..complexitycsg|]}||fqSr r )r1r )r?r r sz<_rank.._permute_complexity_right..cSsg|]\}}|qSr r )r1r rr r rr@r)Z orientation)rrsortedZpermute)r/r"complexZpermr )r/r?r"r_permute_complexity_rights z(_rank.._permute_complexity_rightrrcg|]}|qSr r r1xr3r rr@rAz_rank..FcrEr r rFr3r rr@rANr3Tr-)r8rr9r rZdetr0len) r/r"rrDr#Zzerosdrr;r:r r3r_ranks,   rKc Cs<t|tr|nt}t||||ddd\}}}|r||f}|S)aReturn reduced row-echelon form of matrix and indices of pivot vars. Parameters ========== iszerofunc : Function A function used for detecting whether an element can act as a pivot. ``lambda x: x.is_zero`` is used by default. simplify : Function A function used to simplify elements when looking for a pivot. By default SymPy's ``simplify`` is used. pivots : True or False If ``True``, a tuple containing the row-reduced matrix and a tuple of pivot columns is returned. If ``False`` just the row-reduced matrix is returned. normalize_last : True or False If ``True``, no pivots are normalized to `1` until after all entries above and below each pivot are zeroed. This means the row reduction algorithm is fraction free until the very last step. If ``False``, the naive row reduction procedure is used where each pivot is normalized to be `1` before row operations are used to zero above and below the pivot. Examples ======== >>> from sympy import Matrix >>> from sympy.abc import x >>> m = Matrix([[1, 2], [x, 1 - 1/x]]) >>> m.rref() (Matrix([ [1, 0], [0, 1]]), (0, 1)) >>> rref_matrix, rref_pivots = m.rref() >>> rref_matrix Matrix([ [1, 0], [0, 1]]) >>> rref_pivots (0, 1) Notes ===== The default value of ``normalize_last=True`` can provide significant speedup to row reduction, especially on matrices with symbols. However, if you depend on the form row reduction algorithm leaves entries of the matrix, set ``noramlize_last=False`` T)r%r&r7) r/r"rr:r$r#rr'r;r r r_rrefs7 rLN)TTT)typesrZsympy.simplify.simplifyrr9rrZ utilitiesrrZ determinantrr,r0r6r<rKrLr r r rs   r F