Numeric write-in place facility
David Ascher
da at ski.org
Mon Nov 29 16:11:41 EST 1999
On Mon, 29 Nov 1999, Ionel Simionescu wrote:
> Hi,
>
> In a post on the wxPython list, Markus Gritsch suggested that array ops such
> as
> a = a+b
> can be done faster by using write-in place:
> Numric.add(a,b,a)
>
> Playing around I see now that other ufuncs allow a write-in target
> specification as their last argument. For example,
>
> Numeric.sqrt(a,b)
>
> will put the result in b (if its dimension and type are Ok).
>
> The docs do not tell much about this.
> Can anyone confirm/clarify/comment ?
1) Confirm: yes
2) Clarify: well, I think you pretty much summed it up
3) Comment: Watch out for 'slices'. If you do
a = arange(10)
b = a[::-1]
add(a,b,b)
print b
you might be suprised =)
--david ascher
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