GitHub PushEvent at 2014-12-02 18:40:48
Repository: sympy
Actor: smichr
Payload: {"shas":[["253b291ce5a0bd1d4a5076ddfb9798cd712517f0","b274abc493535ae88cb3a0742f63e38c9241d67c@gmail.com","recast vanilla symbols as reals","Chris Smith",true],["39a0467cb0726ebf15a02ffbad9a9f7882502bcb","b274abc493535ae88cb3a0742f63e38c9241d67c@gmail.com","8545: discard False conditions in reduce_abs before calling reduce_rational","Chris Smith",true],["0d24ee7a4d055ff0a05fc3010a3e8f90b0af8440","b274abc493535ae88cb3a0742f63e38c9241d67c@gmail.com","add numerically_zero to randtest.py\n\nIt was initially tempting to compute an approximation for the error in\nthe expression by computing a value at n=2 and another at n=4 and taking\nthe difference, but the following shows how that can be unreliable:\nwith\n>>> eq = -x - 1 + (-x**2 + 1)/(-x + 1) and\n>>> r = {x: 148683004974611/S(50000000000000) -\n...         144151475495133*I/1000000000000000}\n>>> for maxn in range(1,100):\n...   a, b = [z.n(i,maxn=maxn) for i in (2,4)]\n...   if abs(b) > abs(b-a): print maxn\n...\n10\n11\n12\n>>>\n\nSo at those values of maxn it looks like the computed value is larger than\nthe error in the computation. Unless there is a sound way to compute the\nerror in the expression (quickly) then this, at least, is *not* a way to do it.","Chris Smith",true],["81845ccae6cb04bf19af7bf5537f4f10d73aaa53","b274abc493535ae88cb3a0742f63e38c9241d67c@gmail.com","allow prec=None to signify an autoestimate of the error","Chris Smith",true]],"size":4,"ref":"refs/heads/improve_relational","head":"81845ccae6cb04bf19af7bf5537f4f10d73aaa53"}