[Numpy-discussion] average() or mean() errors
Stefan van der Walt
stefan at sun.ac.za
Fri Jan 26 12:27:36 EST 2007
On Tue, Jan 23, 2007 at 08:29:47PM -0500, Daniel Smith wrote:
> When calling the average() or mean() functions on a small array (3
> numbers), I am seeing significant numerical errors (on the order of 1%
> with data to 8 significant digits). The code I am using is essentially:
>
> A = zeros(3)
> A[i] = X
> B = average(A)
I'm not sure I understand:
In [7]: A = N.zeros(3)
In [8]: A[1] = 3.
In [9]: N.average(A)
Out[9]: 1.0
In [11]: A[0] = 2.
In [12]: N.average(A)
Out[12]: 1.66666666667
In [13]: (2+3+0)/3.
Out[13]: 1.6666666666666667
In [14]: for i in range(1000):
....: A = N.random.rand(3)
....: assert N.average(A) == N.sum(A)/3.
Maybe you can give a specific code snippet?
Cheers
Stéfan
More information about the NumPy-Discussion
mailing list