On Monday, January 21, 2013 3:28:29 PM UTC, Simon King wrote:
> OK, then we should at least fix the documentation of LLL_gram.
>
Our LLL_gram does this:
if self._nrows != self._ncols:
raise ArithmeticError("self must be a square matrix")
n = self.nrows()
# maybe should be /unimodular/ matrices ?
P = self._pari_()
try:
U = P.lllgramint()
except (RuntimeError, ArithmeticError), msg:
raise ValueError("not a definite matrix")
MS = matrix_space.MatrixSpace(ZZ,n)
U = MS(U.python())
# Fix last column so that det = +1
if U.det() == -1:
for i in range(n):
U[i,n-1] = - U[i,n-1]
besides changing documentation we should also replace call to (deprecated)
lllgramint() by a call to qflllgram().
And yes, if the time difference is so large that is an obvious sign we can
speed-up the current test for positive-definiteness.
Cheers,
J
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