Re: [racket-dev] expected timing difference between fft-complex-forward and fft-complex-radix2-forward?

2010-10-19 Thread Doug Williams
On my laptop: #lang racket (require fft.rkt) (define v (build-vector 16384 (lambda (i) (random (define v1 (vector-copy v)) (collect-garbage) (collect-garbage) (collect-garbage) (time (fft-complex-radix2-forward v1)) (define v2 (vector-copy v)) (collect-garbage) (collect-garbage)

Re: [racket-dev] expected timing difference between fft-complex-forward and fft-complex-radix2-forward?

2010-10-19 Thread John Clements
On Oct 19, 2010, at 5:17 AM, Doug Williams wrote: On my laptop: #lang racket (require fft.rkt) (define v (build-vector 16384 (lambda (i) (random (define v1 (vector-copy v)) (collect-garbage) (collect-garbage) (collect-garbage) (time (fft-complex-radix2-forward v1))

Re: [racket-dev] expected timing difference between fft-complex-forward and fft-complex-radix2-forward?

2010-10-18 Thread Doug Williams
When I first ran with vectors of 8192, I got exactly the opposite - the radix-2 version was much slower (although still 500ms). But, when I looked, the longer time was almost exclusively GC - it just happen to hit that particular call. When I put a (collect-garbage) before each call, they were

Re: [racket-dev] expected timing difference between fft-complex-forward and fft-complex-radix2-forward?

2010-10-18 Thread John Clements
On Oct 18, 2010, at 9:25 AM, Doug Williams wrote: When I first ran with vectors of 8192, I got exactly the opposite - the radix-2 version was much slower (although still 500ms). But, when I looked, the longer time was almost exclusively GC - it just happen to hit that particular call.

[racket-dev] expected timing difference between fft-complex-forward and fft-complex-radix2-forward?

2010-10-14 Thread John Clements
On a vector of length 8192 (a power of 2, natch), fft-complex-radix2-forward takes about 1/8 of a second (lost in the noise, essentially), but fft-complex-forward takes more than 24 seconds, a difference of about 200x. They do produce the same answers, up to differences of 1e-4 in the