Re: [Pixman] [PATCH 06/15] pixman-filter: reduced number of samples in Simpson's integration

[Oded Gabbay]

On Fri, Dec 18, 2015 at 12:17 AM, Bill Spitzak  wrote:
> Ok to squash them together. Do you want me to do that?
>
Yes. There will definitely v7 of the patchset (which most likely will
be the version getting merged into the tree), so do it in that
version.

Oded

> It actually does not increase the runtime, because the two loops are only
> adding every *other* sample. Thus the same number of samples are computed.
>

> On Thu, Dec 17, 2015 at 1:23 PM, Oded Gabbay  wrote:
>>
>> On Sat, Dec 12, 2015 at 8:06 PM,   wrote:
>> > From: Bill Spitzak 
>> >
>> > With the cubic fix this is plenty accurate enough, far in excess of the
>> > pixman
>> > fixed-point error limit. Likely even 16 samples is too many.
>> > ---
>> >  pixman/pixman-filter.c | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
>> > index 7c1da0d..4aafa51 100644
>> > --- a/pixman/pixman-filter.c
>> > +++ b/pixman/pixman-filter.c
>> > @@ -190,7 +190,7 @@ integral (pixman_kernel_t reconstruct, double x1,
>> >  else
>> >  {
>> > /* Integration via Simpson's rule */
>> > -#define N_SEGMENTS 128
>> > +#define N_SEGMENTS 16
>> >  #define SAMPLE(a1, a2)
>> > \
>> > (filters[reconstruct].func ((a1)) * filters[sample].func ((a2) /
>> > scale))
>> >
>> > --
>> > 1.9.1
>> >
>> > ___
>> > Pixman mailing list
>> > Pixman@lists.freedesktop.org
>> > http://lists.freedesktop.org/mailman/listinfo/pixman
>>
>> I think it is better to just squash this patch into the previous one,
>> as it closely related and actually makes more sense to put them
>> together so we can see the run time hasn't increased but actually
>> decreased.
>>
>>   Oded
>
>
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Re: [Pixman] [PATCH 06/15] pixman-filter: reduced number of samples in Simpson's integration

[Oded Gabbay]

On Sat, Dec 12, 2015 at 8:06 PM,   wrote:
> From: Bill Spitzak 
>
> With the cubic fix this is plenty accurate enough, far in excess of the pixman
> fixed-point error limit. Likely even 16 samples is too many.
> ---
>  pixman/pixman-filter.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
> index 7c1da0d..4aafa51 100644
> --- a/pixman/pixman-filter.c
> +++ b/pixman/pixman-filter.c
> @@ -190,7 +190,7 @@ integral (pixman_kernel_t reconstruct, double x1,
>  else
>  {
> /* Integration via Simpson's rule */
> -#define N_SEGMENTS 128
> +#define N_SEGMENTS 16
>  #define SAMPLE(a1, a2) \
> (filters[reconstruct].func ((a1)) * filters[sample].func ((a2) / 
> scale))
>
> --
> 1.9.1
>
> ___
> Pixman mailing list
> Pixman@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/pixman

I think it is better to just squash this patch into the previous one,
as it closely related and actually makes more sense to put them
together so we can see the run time hasn't increased but actually
decreased.

  Oded
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Re: [Pixman] [PATCH 06/15] pixman-filter: reduced number of samples in Simpson's integration

[Bill Spitzak]

Ok to squash them together. Do you want me to do that?

It actually does not increase the runtime, because the two loops are only
adding every *other* sample. Thus the same number of samples are computed.

On Thu, Dec 17, 2015 at 1:23 PM, Oded Gabbay  wrote:

> On Sat, Dec 12, 2015 at 8:06 PM,   wrote:
> > From: Bill Spitzak 
> >
> > With the cubic fix this is plenty accurate enough, far in excess of the
> pixman
> > fixed-point error limit. Likely even 16 samples is too many.
> > ---
> >  pixman/pixman-filter.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
> > index 7c1da0d..4aafa51 100644
> > --- a/pixman/pixman-filter.c
> > +++ b/pixman/pixman-filter.c
> > @@ -190,7 +190,7 @@ integral (pixman_kernel_t reconstruct, double x1,
> >  else
> >  {
> > /* Integration via Simpson's rule */
> > -#define N_SEGMENTS 128
> > +#define N_SEGMENTS 16
> >  #define SAMPLE(a1, a2) \
> > (filters[reconstruct].func ((a1)) * filters[sample].func ((a2) /
> scale))
> >
> > --
> > 1.9.1
> >
> > ___
> > Pixman mailing list
> > Pixman@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/pixman
>
> I think it is better to just squash this patch into the previous one,
> as it closely related and actually makes more sense to put them
> together so we can see the run time hasn't increased but actually
> decreased.
>
>   Oded
>
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[Pixman] [PATCH 06/15] pixman-filter: reduced number of samples in Simpson's integration

[spitzak]

From: Bill Spitzak 

With the cubic fix this is plenty accurate enough, far in excess of the pixman
fixed-point error limit. Likely even 16 samples is too many.
---
 pixman/pixman-filter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
index 7c1da0d..4aafa51 100644
--- a/pixman/pixman-filter.c
+++ b/pixman/pixman-filter.c
@@ -190,7 +190,7 @@ integral (pixman_kernel_t reconstruct, double x1,
 else
 {
/* Integration via Simpson's rule */
-#define N_SEGMENTS 128
+#define N_SEGMENTS 16
 #define SAMPLE(a1, a2) \
(filters[reconstruct].func ((a1)) * filters[sample].func ((a2) / scale))

-- 
1.9.1

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