MAINT:linalg:Remove memcpy from lu

Author: ilayn

scipy/linalg/_decomp_lu_cython.pyx

@@ -2,8 +2,6 @@
 
 import cython
 from cpython.mem cimport PyMem_Malloc, PyMem_Free
-from libc.string cimport memcpy
-
 from scipy.linalg.cython_lapack cimport sgetrf, dgetrf, cgetrf, zgetrf
 from scipy.linalg._cythonized_array_utils cimport lapack_t, swap_c_and_f_layout
 
@@ -103,7 +101,9 @@ cdef void lu_decompose(cnp.ndarray[lapack_t, ndim=2] a,
  # as final. Solution without argsort : ipiv[perm] = np.arange(m)
  for ind1 in range(m):
  ipiv[perm[ind1]] = ind1
- memcpy(&perm[0], ipiv, m*sizeof(int))
+ for ind1 in range(m):
+ perm[ind1] = ipiv[ind1]
+
  finally:
  PyMem_Free(ipiv)
 
@@ -135,24 +135,22 @@ cdef void lu_decompose(cnp.ndarray[lapack_t, ndim=2] a,
  # rows from b as dictated by perm
 
  if m > n:
- memcpy(bb, &a[0, 0], m*mn*sizeof(lapack_t))
+ b[:, :] = a[:, :]
+ # memcpy(bb, &a[0, 0], m*mn*sizeof(lapack_t))
  for ind1 in range(m):
  if perm[ind1] == ind1:
  continue
  else:
- memcpy(&a[ind1, 0],
- bb + (perm[ind1]*mn), # row stride
- mn*sizeof(lapack_t)) # copy one row of memory
+ a[ind1, :] = b[perm[ind1], :]
 
  else: # same but for lu array
- memcpy(bb, &lu[0, 0], mn*n*sizeof(lapack_t))
+ b[:mn, :mn] = lu[:, :]
+ # memcpy(bb, &lu[0, 0], mn*n*sizeof(lapack_t))
  for ind1 in range(mn):
  if perm[ind1] == ind1:
  continue
  else:
- memcpy(&lu[ind1, 0],
- bb + (perm[ind1]*mn),
- mn*sizeof(lapack_t))
+ lu[ind1, :] = b[perm[ind1], :mn]
 
 
 @cython.nonecheck(False)