Joel VanderWerf
9/22/2003 9:15:00 PM
Johann Hibschman wrote:
> "Robert Klemme" <bob.news@gmx.net> wrote in message news:<bkmq5r$3dhd5$2@ID-52924.news.uni-berlin.de>...
>
>
>>You can''t. And you don''t need to. As others pointed out already, Ruby
>>treats all the assignment arithmetic operators as shortcuts and invokes
>>the appropriate operator. So
>
>
> Er. "You don''t need to" is rather extreme. What about numerical cases?
>
> i.e., if m is a large matrix, then "m += 1" and "m = m + 1" are rather
> different beasts, since the "obvioius" interpretation of the first involves
> simply incrementing the matrix in place, while the second involves a
> copy.
>
> Is there a standard work-around for this? This was one of the reasons I
> stuck with python over ruby, but I''ve got to admit that I didn''t spend a
> huge amount of time researching.
narray has
self.add! other
self.sbt! other
self.mul! other
self.div! other
self.mod! other
which presumably are in-place ops. Anyway, they are faster than *= and
friends:
user system total real
warmup 16.980000 2.850000 19.830000 ( 22.501646)
using *= and /= 0.400000 0.050000 0.450000 ( 0.462865)
using mul! and div! 0.160000 0.020000 0.180000 ( 0.181544)
using no ops 0.000000 0.000000 0.000000 ( 0.006473)
(on PIII850).
=================================
require ''narray''
require ''benchmark''
Benchmark.bm(22) do |test|
reps = 10_000
m = NMatrix.float(100,100).fill(1)
test.report("warmup") do
(1..reps).each do |i|
m *= i
m /= i
end
end
m = NMatrix.float(3,3).fill(1)
test.report("using *= and /=") do
(1..reps).each do |i|
m *= i
m /= i
end
end
m = NMatrix.float(3,3).fill(1)
test.report("using mul! and div!") do
(1..reps).each do |i|
m.mul! i
m.div! i
end
end
m = NMatrix.float(3,3).fill(1)
test.report("using no ops") do
(1..reps).each do |i|
end
end
end