Fix spelling typos in documentation

Author: 7ayushgupta

pymc3/math.py

@@ -319,7 +319,7 @@ def invprobit(x):
 def expand_packed_triangular(n, packed, lower=True, diagonal_only=False):
     r"""Convert a packed triangular matrix into a two dimensional array.
 
-    Triangular matrices can be stored with better space efficiancy by
+    Triangular matrices can be stored with better space efficiency by
     storing the non-zero values in a one-dimensional array. We number
     the elements by row like this (for lower or upper triangular matrices):
 
@@ -340,7 +340,7 @@ def expand_packed_triangular(n, packed, lower=True, diagonal_only=False):
         If true, return only the diagonal of the matrix.
     """
     if packed.ndim != 1:
-        raise ValueError("Packed triagular is not one dimensional.")
+        raise ValueError("Packed triangular is not one dimensional.")
     if not isinstance(n, int):
         raise TypeError("n must be an integer")