Coverage for local/lib/python2.7/site-packages/sage/libs/ntl/ntl_GF2EContext.pyx : 57%

#***************************************************************************** 

# Copyright (C) 2005 William Stein <wstein@gmail.com> 

# 

# Distributed under the terms of the GNU General Public License (GPL) 

# 

# This code is distributed in the hope that it will be useful, 

# but WITHOUT ANY WARRANTY; without even the implied warranty of 

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 

# General Public License for more details. 

# 

# The full text of the GPL is available at: 

# 

# http://www.gnu.org/licenses/ 

#***************************************************************************** 

from __future__ import absolute_import 

include 'misc.pxi' 

include 'decl.pxi' 

import weakref 

GF2EContextDict = {} 

cdef class ntl_GF2EContext_class(object): 

def __init__(self, ntl_GF2X v): 

""" 

EXAMPLES: 

# You can construct contexts manually. 

sage: ctx = ntl.GF2EContext(ntl.GF2X([1,1,0,1])) 

sage: n1 = ntl.GF2E([1,1],ctx) 

sage: n1 

[1 1] 

# or You can construct contexts implicitly. 

sage: n2 = ntl.GF2E([0,1], ntl.GF2X([1,1,0,1])) 

sage: n2 

[0 1] 

sage: ntl.GF2E(2, GF(2^8,'a'))+ntl.GF2E([0,1],ctx) 

Traceback (most recent call last): 

... 

ValueError: You can not perform arithmetic with elements in different fields. 

sage: n2+n1 # Mismatched moduli: It will go BOOM! 

[1] 

""" 

pass 

def __cinit__(self, ntl_GF2X v): 

self.x = GF2EContext_c(v.x) 

self.m = v 

def __reduce__(self): 

""" 

EXAMPLES: 

sage: c = ntl.GF2EContext(GF(2^5,'b')) 

sage: loads(dumps(c)) is c 

True 

""" 

return ntl_GF2EContext, (self.m,) 

def __repr__(self): 

""" 

Returns a print representation of self. 

EXAMPLES: 

sage: c = ntl.GF2EContext(GF(2^16,'a')) 

sage: c 

NTL modulus [1 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 1] 

""" 

return "NTL modulus %s"%(self.m) 

def modulus(self): 

""" 

Return the current modulus associated to this 

context. 

EXAMPLES: 

sage: c = ntl.GF2EContext(GF(2^7,'foo')) 

sage: c.modulus() 

[1 1 0 0 0 0 0 1] 

""" 

return self.m 

def restore(self): 

""" 

EXAMPLES: 

sage: c1 = ntl.GF2E([0,1],GF(2^4,'a')) ; c2 = ntl.GF2E([1,0,1],GF(2^4,'a')) 

sage: c1+c2 

[1 1 1] 

sage: d1 = ntl.GF2E([0,1],GF(2^5,'a')) ; d2 = ntl.GF2E([0,0,1],GF(2^5,'a')) 

sage: d1*d2 ## indirect doctest 

[0 0 0 1] 

""" 

self.restore_c() 

cdef void restore_c(self): 

self.x.restore() 

def ntl_GF2EContext( v ): 

""" 

Create a new GF2EContext. 

EXAMPLES: 

sage: c = ntl.GF2EContext(GF(2^2,'a')) 

sage: n1 = ntl.GF2E([0,1],c) 

sage: n1 

[0 1] 

""" 

v = ntl_GF2X(v) 

if (GF2X_deg((<ntl_GF2X>v).x) < 1): 

raise ValueError("%s is not a valid modulus." % v) 

key = hash(v) 

if key in GF2EContextDict: 

context = GF2EContextDict[key]() 

if context is not None: 

return context 

context = ntl_GF2EContext_class(v) 

GF2EContextDict[key] = weakref.ref(context) 

return context