X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=mjo%2Fcone%2Fdoubly_nonnegative.py;h=1fb350cb46559a55b982ee3de15678e02d5a04de;hb=b760d6ffe2554def684bf1118fff22072b8cf781;hp=7d39061d21dae6e2f9795cc63ccffe91c220cd0a;hpb=2fa2a7a2f6a5d5f1628a4f5cf3301d5e7f670038;p=sage.d.git

diff --git a/mjo/cone/doubly_nonnegative.py b/mjo/cone/doubly_nonnegative.py
index 7d39061..1fb350c 100644
--- a/mjo/cone/doubly_nonnegative.py
+++ b/mjo/cone/doubly_nonnegative.py
@@ -1,4 +1,4 @@
-"""
+r"""
 The doubly-nonnegative cone in `S^{n}` is the set of all such matrices
 that both,
 
@@ -13,13 +13,9 @@ It is represented typically by either `\mathcal{D}^{n}` or
 
 from sage.all import *
 
-# Sage doesn't load ~/.sage/init.sage during testing (sage -t), so we
-# have to explicitly mangle our sitedir here so that our module names
-# resolve.
-from os.path import abspath
-from site import addsitedir
-addsitedir(abspath('../../'))
-from mjo.cone.symmetric_psd import factor_psd, is_symmetric_psd, random_psd
+from mjo.cone.symmetric_psd import (factor_psd,
+                                    is_symmetric_psd,
+                                    random_symmetric_psd)
 from mjo.matrix_vector import isomorphism
 
 
@@ -62,7 +58,7 @@ def is_doubly_nonnegative(A):
         raise ValueError.new(msg)
 
     # Check that all of the entries of ``A`` are nonnegative.
-    if not all([ a >= 0 for a in A.list() ]):
+    if not all( a >= 0 for a in A.list() ):
         return False
 
     # It's nonnegative, so all we need to do is check that it's
@@ -72,7 +68,7 @@ def is_doubly_nonnegative(A):
 
 
 def is_admissible_extreme_rank(r, n):
-    """
+    r"""
     The extreme matrices of the doubly-nonnegative cone have some
     restrictions on their ranks. This function checks to see whether the
     rank ``r`` would be an admissible rank for an ``n``-by-``n`` matrix.
@@ -375,8 +371,8 @@ def is_extreme_doubly_nonnegative(A):
     # whenever we come across an index pair `$(i,j)$` with
     # `$A_{ij} = 0$`.
     spanning_set = []
-    for j in range(0, A.ncols()):
-        for i in range(0,j):
+    for j in range(A.ncols()):
+        for i in range(j):
             if A[i,j] == 0:
                 M = A.matrix_space()
                 S = X.transpose() * (stdE(M,i,j) + stdE(M,j,i)) * X
@@ -464,10 +460,10 @@ def random_doubly_nonnegative(V, accept_zero=True, rank=None):
 
     # Generate random symmetric positive-semidefinite matrices until
     # one of them is nonnegative, then return that.
-    A = random_psd(V, accept_zero, rank)
+    A = random_symmetric_psd(V, accept_zero, rank)
 
-    while not all([ x >= 0 for x in A.list() ]):
-        A = random_psd(V, accept_zero, rank)
+    while not all( x >= 0 for x in A.list() ):
+        A = random_symmetric_psd(V, accept_zero, rank)
 
     return A
 
@@ -534,7 +530,7 @@ def random_extreme_doubly_nonnegative(V, accept_zero=True, rank=None):
 
     """
 
-    if not is_admissible_extreme_rank(rank, V.dimension()):
+    if rank is not None and not is_admissible_extreme_rank(rank, V.dimension()):
         msg = 'Rank %d not possible in dimension %d.'
         raise ValueError(msg % (rank, V.dimension()))