Hi folks,
I like the floor function that is automatically loaded during each
terminal session. And I think it's the function
sage.calculus.calculus.Function_floor. I'm trying to use that function
in the patch up at #5827. In that patch, I implemented a module called
"sage/crypto/knapsack" with only the class "Superincreasing" at the
moment. In the method "_largest_less_than" of that class, I've
imported the above floor function by doing
from sage.calculus.calculus import Function_floor as floor
at the beginning of the method. However, when it comes to using the
said method, I received this error
*** begin Sage transcript ***
sage: L = [2, 3, 7, 25, 67, 179, 356, 819]
sage: Superincreasing(L)._largest_less_than(207)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/home/mvngu/.sage/temp/mod.math.washington.edu/9866/_home_mvngu__sage_init_sage_0.py
in <module>()
/scratch/mvngu/sage-3.4.1.rc3/local/lib/python2.5/site-packages/sage/crypto/knapsack.pyc
in _largest_less_than(self, N)
167 high = len(self._seq) - 1
168 while low <= high:
--> 169 mid = Integer(floor((low + high) / 2))
170 if N == self._seq[mid]:
171 return self._seq[mid]
/scratch/mvngu/sage-3.4.1.rc3/local/lib/python2.5/site-packages/sage/rings/integer.so
in sage.rings.integer.Integer.__init__ (sage/rings/integer.c:6484)()
/scratch/mvngu/sage-3.4.1.rc3/local/lib/python2.5/site-packages/sage/calculus/calculus.pyc
in _integer_(self, ZZ)
1769 -3
1770 """
-> 1771 return Integer(repr(self))
1772
1773 def _add_(self, right):
/scratch/mvngu/sage-3.4.1.rc3/local/lib/python2.5/site-packages/sage/rings/integer.so
in sage.rings.integer.Integer.__init__ (sage/rings/integer.c:6446)()
TypeError: unable to convert x (=floor) to an integer
*** end Sage transcript ***
To get around the problem, I changed the import statement
from sage.calculus.calculus import Function_floor as floor
to
from math import floor
But this floor function can return a floating point number, so I would
need to coerce its result to type Integer. Did I miss any other import
statements to make sage.calculus.calculus import Function_floor
return a result of type integer?
--
Regards
Minh Van Nguyen
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