code: def _make_interp_per_full_matr(x, y, t, k):
      """
      Returns a solution of a system for B-spline interpolation with periodic
      boundary conditions. First ``k - 1`` rows of matrix are condtions of
      periodicity (continuity of ``k - 1`` derivatives at the boundary points).
      Last ``n`` rows are interpolation conditions.
      RHS is ``k - 1`` zeros and ``n`` ordinates in this case.
  
      Parameters
      ----------
      x : 1-D array, shape (n,)
          Values of x - coordinate of a given set of points.
      y : 1-D array, shape (n,)
          Values of y - coordinate of a given set of points.
      t : 1-D array, shape(n+2*k,)
          Vector of knots.
      k : int
          The maximum degree of spline
  
      Returns
      -------
      c : 1-D array, shape (n+k-1,)
          B-spline coefficients
  
      Notes
      -----
      ``t`` is supposed to be taken on circle.
  
      """
  
      x, y, t = map(np.asarray, (x, y, t))
  
      n = x.size
      # LHS: the collocation matrix + derivatives at edges
      matr = np.zeros((n + k - 1, n + k - 1))
  
      # derivatives at x[0] and x[-1]:
      for i in range(k - 1):
          bb = _bspl.evaluate_all_bspl(t, k, x[0], k, nu=i + 1)
          matr[i, : k + 1] += bb
          bb = _bspl.evaluate_all_bspl(
              t, k, x[-1], n + k - 1, nu=i + 1
          )[:-1]
          matr[i, -k:] -= bb
  
      # collocation matrix
      for i in range(n):
          xval = x[i]
          # find interval
          if xval == t[k]:
              left = k
          else:
              left = np.searchsorted(t, xval) - 1
  
          # fill a row
          bb = _bspl.evaluate_all_bspl(t, k, xval, left)
          matr[i + k - 1, left - k : left + 1] = bb
  
      # RHS
      b = np.r_[[0] * (k - 1), y]
  
      c = solve(matr, b)
      return c
  
imports: import operator
  import numpy
  from numpy.core.multiarray import normalize_axis_index
  from scipy.linalg import get_lapack_funcs, LinAlgError, cholesky_banded, cho_solve_banded, solve, solve_banded
  from .None import _bspl
  from .None import _fitpack_impl
  from .None import _fitpack
  from scipy._lib._util import prod
label_desc: Use image node_id 9 for calling a global function with example usage: _make_interp_per_full_matr(x, y, t, k) and returns: c