diff --git a/src/qailo/mps/__init__.py b/src/qailo/mps/__init__.py
index 27da342..c8c0fe2 100644
--- a/src/qailo/mps/__init__.py
+++ b/src/qailo/mps/__init__.py
@@ -1,15 +1,20 @@
-from .canonical import is_canonical
-from .mps import MPS, check, norm, product_state
+from .canonical import check_mps, is_canonical
+from .mps import MPS
+from .norm import norm
+from .num_qubits import num_qubits
+from .product_state import product_state
 from .state_vector import state_vector
 from .svd import compact_svd, tensor_svd
 
 __all__ = [
     is_canonical,
+    check_mps,
     MPS,
-    check,
     norm,
-    product_state,
+    norm,
+    num_qubits,
     compact_svd,
     tensor_svd,
+    product_state,
     state_vector,
 ]
diff --git a/src/qailo/mps/canonical.py b/src/qailo/mps/canonical.py
index 0f1f97f..06d87d6 100644
--- a/src/qailo/mps/canonical.py
+++ b/src/qailo/mps/canonical.py
@@ -1,6 +1,6 @@
 import numpy as np
 
-from .type import num_qubits
+from .num_qubits import num_qubits
 
 
 def is_canonical(m):
@@ -16,3 +16,35 @@ def is_canonical(m):
         return True
     else:
         return False
+
+
+def check_mps(m):
+    """
+    Check the shape of mps
+    """
+    n = num_qubits(m)
+
+    # tensor shape
+    dims = []
+    assert m.tensors[0].shape[0] == 1
+    dims.append(m.tensors[0].shape[0])
+    for t in range(1, n - 1):
+        dims.append(m.tensors[t].shape[0])
+        assert m.tensors[t].shape[0] == m.tensors[t - 1].shape[2]
+        assert m.tensors[t].shape[2] == m.tensors[t + 1].shape[0]
+    assert m.tensors[n - 1].shape[2] == 1
+    dims.append(m.tensors[n - 1].shape[0])
+    dims.append(m.tensors[n - 1].shape[2])
+    # print(dims)
+
+    # qubit <-> tensor mapping
+    for q in range(n):
+        assert m.t2q[m.q2t[q]] == q
+    for t in range(n):
+        assert m.q2t[m.t2q[t]] == t
+
+    # canonical position
+    assert m.cp[0] in range(n)
+    assert m.cp[1] in range(n)
+
+    return True
diff --git a/src/qailo/mps/mps.py b/src/qailo/mps/mps.py
index 14b30b0..45c743e 100644
--- a/src/qailo/mps/mps.py
+++ b/src/qailo/mps/mps.py
@@ -2,6 +2,7 @@
 
 from ..operator import type as op
 from ..operator.swap import swap
+from .num_qubits import num_qubits
 from .svd import tensor_svd
 
 
@@ -34,9 +35,6 @@ def __init__(self, tensors, q2t=None, t2q=None, cp=None):
         self.cp = cp if cp is not None else [0, n - 1]
         assert 0 <= self.cp[0] and self.cp[0] <= self.cp[1] and self.cp[1] < n
 
-    def num_qubits(self):
-        return len(self.tensors)
-
     def canonicalize(self, p0, p1=None):
         p1 = p0 if p1 is None else p1
         n = len(self.tensors)
@@ -81,7 +79,7 @@ def _swap_tensors(self, s, maxdim=None):
         """
         swap neighboring two tensors at s and s+1
         """
-        assert s in range(0, self.num_qubits() - 1)
+        assert s in range(0, num_qubits(self) - 1)
         self._apply_two(swap(), s, maxdim=maxdim)
         p0, p1 = self.t2q[s], self.t2q[s + 1]
         self.q2t[p0], self.q2t[p1] = s + 1, s
@@ -118,7 +116,7 @@ def check(mps):
     """
     Check the shape of mps
     """
-    n = mps.num_qubits()
+    n = num_qubits(mps)
 
     # tensor shape
     dims = []
@@ -144,21 +142,3 @@ def check(mps):
     assert mps.cp[1] in range(n)
 
     return True
-
-
-def product_state(n, c=0):
-    assert n > 0
-    tensors = []
-    for t in range(n):
-        tensor = np.zeros((1, 2, 1))
-        tensor[0, (c >> (n - t - 1)) & 1, 0] = 1
-        tensors.append(tensor)
-    return MPS(tensors)
-
-
-def norm(m):
-    A = np.identity(2)
-    for t in range(m.num_qubits()):
-        A = np.einsum("ij,jkl->ikl", A, m.tensors[t])
-        A = np.einsum("ijk,ijl->kl", A, m.tensors[t].conj())
-    return np.sqrt(np.trace(A))
diff --git a/src/qailo/mps/norm.py b/src/qailo/mps/norm.py
new file mode 100644
index 0000000..ae0e987
--- /dev/null
+++ b/src/qailo/mps/norm.py
@@ -0,0 +1,11 @@
+import numpy as np
+
+from .num_qubits import num_qubits
+
+
+def norm(m):
+    A = np.identity(2)
+    for t in range(num_qubits(m)):
+        A = np.einsum("ij,jkl->ikl", A, m.tensors[t])
+        A = np.einsum("ijk,ijl->kl", A, m.tensors[t].conj())
+    return np.sqrt(np.trace(A))
diff --git a/src/qailo/mps/num_qubits.py b/src/qailo/mps/num_qubits.py
new file mode 100644
index 0000000..c4d8c11
--- /dev/null
+++ b/src/qailo/mps/num_qubits.py
@@ -0,0 +1,2 @@
+def num_qubits(m):
+    return len(m.tensors)
diff --git a/src/qailo/mps/product_state.py b/src/qailo/mps/product_state.py
new file mode 100644
index 0000000..fcb7b00
--- /dev/null
+++ b/src/qailo/mps/product_state.py
@@ -0,0 +1,13 @@
+import numpy as np
+
+from .mps import MPS
+
+
+def product_state(n, c=0):
+    assert n > 0
+    tensors = []
+    for t in range(n):
+        tensor = np.zeros((1, 2, 1))
+        tensor[0, (c >> (n - t - 1)) & 1, 0] = 1
+        tensors.append(tensor)
+    return MPS(tensors)
diff --git a/src/qailo/mps/state_vector.py b/src/qailo/mps/state_vector.py
index 6be6cca..e023cc2 100644
--- a/src/qailo/mps/state_vector.py
+++ b/src/qailo/mps/state_vector.py
@@ -1,21 +1,22 @@
 import numpy as np
 
 from ..util.strops import letters, replace
-from .type import is_mps, num_qubits
+from .num_qubits import num_qubits
+from .type import is_mps
 
 
-def state_vector(mps):
-    assert is_mps(mps)
-    n = num_qubits(mps)
-    v = mps.tensors[0]
+def state_vector(m):
+    assert is_mps(m)
+    n = num_qubits(m)
+    v = m.tensors[0]
     for t in range(1, n):
         ss_v0 = letters()[: t + 2]
         ss_v1 = letters()[t + 1 : t + 4]
         ss_to = letters()[: t + 1] + letters()[t + 2 : t + 4]
-        v = np.einsum(f"{ss_v0},{ss_v1}->{ss_to}", v, mps.tensors[t])
+        v = np.einsum(f"{ss_v0},{ss_v1}->{ss_to}", v, m.tensors[t])
     v = v.reshape((2,) * n)
     ss_from = letters()[:n]
     ss_to = ss_from
     for p in range(n):
-        ss_to = replace(ss_to, p, ss_from[mps.q2t[p]])
+        ss_to = replace(ss_to, p, ss_from[m.q2t[p]])
     return np.einsum(f"{ss_from}->{ss_to}", v).reshape((2,) * n + (1,))
diff --git a/src/qailo/mps/type.py b/src/qailo/mps/type.py
index 4ff785d..ff51ab5 100644
--- a/src/qailo/mps/type.py
+++ b/src/qailo/mps/type.py
@@ -1,9 +1,5 @@
 from .mps import MPS
 
 
-def is_mps(mps):
-    return isinstance(mps, MPS)
-
-
-def num_qubits(mps):
-    return mps.num_qubits()
+def is_mps(m):
+    return isinstance(m, MPS)
diff --git a/src/qailo/operator/hconj.py b/src/qailo/operator/hconj.py
index 59223be..5b5f7b3 100644
--- a/src/qailo/operator/hconj.py
+++ b/src/qailo/operator/hconj.py
@@ -1,12 +1,11 @@
 import numpy as np
 
-from ..util.strops import letters
 from .type import is_operator, num_qubits
 
 
 def hconj(op):
     assert is_operator(op)
     n = num_qubits(op)
-    ss_from = letters()[: 2 * n]
-    ss_to = ss_from[n : 2 * n] + ss_from[:n]
-    return np.einsum("{}->{}".format(ss_from, ss_to), op).conjugate()
+    ss_from = list(range(2 * n))
+    ss_to = list(range(n, 2 * n)) + list(range(n))
+    return np.einsum(op, ss_from, ss_to).conjugate()
diff --git a/test/mps/test_canonical.py b/test/mps/test_canonical.py
index d50b489..32c24ed 100644
--- a/test/mps/test_canonical.py
+++ b/test/mps/test_canonical.py
@@ -16,7 +16,7 @@ def test_canonical():
     tensors.append(np.random.random((d, 2, 1)))
     mps = q.mps.MPS(tensors)
     norm = q.mps.norm(mps)
-    assert q.mps.check(mps)
+    assert q.mps.check_mps(mps)
 
     for _ in range(n):
         p = np.random.randint(n)
diff --git a/test/mps/test_move.py b/test/mps/test_move.py
index 124b184..6c74f79 100644
--- a/test/mps/test_move.py
+++ b/test/mps/test_move.py
@@ -15,7 +15,7 @@ def test_swap():
         d = dn
     tensors.append(np.random.random((d, 2, 1)))
     mps = q.mps.MPS(tensors)
-    q.mps.check(mps)
+    q.mps.check_mps(mps)
     norm = q.mps.norm(mps)
     v0 = q.sv.vector(q.mps.state_vector(mps))
 
@@ -45,7 +45,7 @@ def test_move():
         d = dn
     tensors.append(np.random.random((d, 2, 1)))
     mps = q.mps.MPS(tensors)
-    q.mps.check(mps)
+    q.mps.check_mps(mps)
     norm = q.mps.norm(mps)
     v0 = q.sv.vector(q.mps.state_vector(mps))
 
diff --git a/test/mps/test_svd.py b/test/mps/test_svd.py
index 0e8004e..0ee7fe5 100644
--- a/test/mps/test_svd.py
+++ b/test/mps/test_svd.py
@@ -3,8 +3,8 @@
 
 
 def test_compact_svd():
-    maxn = 64
-    nt = 64
+    maxn = 16
+    nt = 16
     for _ in range(nt):
         m, n, d = np.random.randint(2, maxn, size=(3,))
         A = np.random.random((m, n))
@@ -22,8 +22,8 @@ def test_compact_svd():
 
 
 def test_svd_left():
-    maxn = 32
-    nt = 64
+    maxn = 16
+    nt = 16
     for _ in range(nt):
         m, n, p, d = np.random.randint(2, maxn, size=(4,))
         T = np.random.random((m, n, p))
@@ -49,8 +49,8 @@ def test_svd_left():
 
 
 def test_svd_right():
-    maxn = 32
-    nt = 64
+    maxn = 16
+    nt = 16
     for _ in range(nt):
         m, n, p, d = np.random.randint(2, maxn, size=(4,))
         T = np.random.random((m, n, p))
@@ -77,7 +77,7 @@ def test_svd_right():
 
 def test_svd_two():
     maxn = 8
-    nt = 64
+    nt = 16
     for _ in range(nt):
         m, n, p, r, d = np.random.randint(2, maxn, size=(5,))
         T = np.random.random((m, n, p, r))