chore: 添加虚拟环境到仓库

- 添加 backend_service/venv 虚拟环境
- 包含所有Python依赖包
- 注意：虚拟环境约393MB，包含12655个文件

backend_service/venv/lib/python3.13/site-packages/sympy/matrices/subspaces.py

@@ -0,0 +1,174 @@
+from .utilities import _iszero
+
+
+def _columnspace(M, simplify=False):
+    """Returns a list of vectors (Matrix objects) that span columnspace of ``M``
+
+    Examples
+    ========
+
+    >>> from sympy import Matrix
+    >>> M = Matrix(3, 3, [1, 3, 0, -2, -6, 0, 3, 9, 6])
+    >>> M
+    Matrix([
+    [ 1,  3, 0],
+    [-2, -6, 0],
+    [ 3,  9, 6]])
+    >>> M.columnspace()
+    [Matrix([
+    [ 1],
+    [-2],
+    [ 3]]), Matrix([
+    [0],
+    [0],
+    [6]])]
+
+    See Also
+    ========
+
+    nullspace
+    rowspace
+    """
+
+    reduced, pivots = M.echelon_form(simplify=simplify, with_pivots=True)
+
+    return [M.col(i) for i in pivots]
+
+
+def _nullspace(M, simplify=False, iszerofunc=_iszero):
+    """Returns list of vectors (Matrix objects) that span nullspace of ``M``
+
+    Examples
+    ========
+
+    >>> from sympy import Matrix
+    >>> M = Matrix(3, 3, [1, 3, 0, -2, -6, 0, 3, 9, 6])
+    >>> M
+    Matrix([
+    [ 1,  3, 0],
+    [-2, -6, 0],
+    [ 3,  9, 6]])
+    >>> M.nullspace()
+    [Matrix([
+    [-3],
+    [ 1],
+    [ 0]])]
+
+    See Also
+    ========
+
+    columnspace
+    rowspace
+    """
+
+    reduced, pivots = M.rref(iszerofunc=iszerofunc, simplify=simplify)
+
+    free_vars = [i for i in range(M.cols) if i not in pivots]
+    basis     = []
+
+    for free_var in free_vars:
+        # for each free variable, we will set it to 1 and all others
+        # to 0.  Then, we will use back substitution to solve the system
+        vec           = [M.zero] * M.cols
+        vec[free_var] = M.one
+
+        for piv_row, piv_col in enumerate(pivots):
+            vec[piv_col] -= reduced[piv_row, free_var]
+
+        basis.append(vec)
+
+    return [M._new(M.cols, 1, b) for b in basis]
+
+
+def _rowspace(M, simplify=False):
+    """Returns a list of vectors that span the row space of ``M``.
+
+    Examples
+    ========
+
+    >>> from sympy import Matrix
+    >>> M = Matrix(3, 3, [1, 3, 0, -2, -6, 0, 3, 9, 6])
+    >>> M
+    Matrix([
+    [ 1,  3, 0],
+    [-2, -6, 0],
+    [ 3,  9, 6]])
+    >>> M.rowspace()
+    [Matrix([[1, 3, 0]]), Matrix([[0, 0, 6]])]
+    """
+
+    reduced, pivots = M.echelon_form(simplify=simplify, with_pivots=True)
+
+    return [reduced.row(i) for i in range(len(pivots))]
+
+
+def _orthogonalize(cls, *vecs, normalize=False, rankcheck=False):
+    """Apply the Gram-Schmidt orthogonalization procedure
+    to vectors supplied in ``vecs``.
+
+    Parameters
+    ==========
+
+    vecs
+        vectors to be made orthogonal
+
+    normalize : bool
+        If ``True``, return an orthonormal basis.
+
+    rankcheck : bool
+        If ``True``, the computation does not stop when encountering
+        linearly dependent vectors.
+
+        If ``False``, it will raise ``ValueError`` when any zero
+        or linearly dependent vectors are found.
+
+    Returns
+    =======
+
+    list
+        List of orthogonal (or orthonormal) basis vectors.
+
+    Examples
+    ========
+
+    >>> from sympy import I, Matrix
+    >>> v = [Matrix([1, I]), Matrix([1, -I])]
+    >>> Matrix.orthogonalize(*v)
+    [Matrix([
+    [1],
+    [I]]), Matrix([
+    [ 1],
+    [-I]])]
+
+    See Also
+    ========
+
+    MatrixBase.QRdecomposition
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Gram%E2%80%93Schmidt_process
+    """
+    from .decompositions import _QRdecomposition_optional
+
+    if not vecs:
+        return []
+
+    all_row_vecs = (vecs[0].rows == 1)
+
+    vecs = [x.vec() for x in vecs]
+    M = cls.hstack(*vecs)
+    Q, R = _QRdecomposition_optional(M, normalize=normalize)
+
+    if rankcheck and Q.cols < len(vecs):
+        raise ValueError("GramSchmidt: vector set not linearly independent")
+
+    ret = []
+    for i in range(Q.cols):
+        if all_row_vecs:
+            col = cls(Q[:, i].T)
+        else:
+            col = cls(Q[:, i])
+        ret.append(col)
+    return ret