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E. Rosten
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 Posted: Fri Jul 29, 2005 4:04 pm Post subject: Floating point template arguments. |
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For all of you who are disapointed at the lack of floating point template
parameters: I have an implementation of floating point done entirely in
templates here:
http://mi.eng.cam.ac.uk/~er258/code/fp_template.html
so you can perform floating point arithmetic and template on the results
freely at compile time
So far basic arithmetic is implemented, as well as a few elementary
functions (exp and sqrt, though not with very good algorithms).
It is now in a usable form: othe main example uses the compile time
floating point arithmetic to generate a static Gaussian convolution
kernel. As well as being more general purpose and more easily modifiable
than a hand coded version, the automatically generated kernel runs 1%
faster (on gcc 4.0.0, x86) than the hand coded version.
It does take 7 minutes to compile, though.
-Ed
--
(You can't go wrong with psycho-rats.) (er258)(@)(eng.cam)(.ac.uk)
/d{def}def/f{/Times findfont s scalefont setfont}d/s{10}d/r{roll}d f 5/m
{moveto}d -1 r 230 350 m 0 1 179{1 index show 88 rotate 4 mul 0 rmoveto}
for /s 15 d f pop 240 420 m 0 1 3 { 4 2 1 r sub -1 r show } for showpage
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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Edson Manoel
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| Posted: Sat Jul 30, 2005 12:34 am Post subject: Re: Floating point template arguments. |
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| Quote: | As well as being more general purpose and more easily modifiable
than a hand coded version, the automatically generated kernel runs
1% faster (on gcc 4.0.0, x86) than the hand coded version.
It does take 7 minutes to compile, though.
|
Congratulations... for doing something like this with template
metaprogramming requires a lot of skill!
I've already done something similar before (but using fixed point
arithmetic), and I came to the conclusion that it is better to just use
a "code generator" to do the convolution and generate the static data
in a header!
The reason for this is that:
- the "metaprogram" (i.e, the code-generating program in this case) is
clearer than a templated version;
- debugging and modifying it is simpler;
- compilation time is *way* faster =)
Edson
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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E. Rosten
Guest
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| Posted: Sat Jul 30, 2005 10:21 am Post subject: Re: Floating point template arguments. |
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On Fri, 29 Jul 2005 20:34:27 -0400, Edson Manoel wrote:
| Quote: | As well as being more general purpose and more easily modifiable
than a hand coded version, the automatically generated kernel runs
1% faster (on gcc 4.0.0, x86) than the hand coded version.
It does take 7 minutes to compile, though.
Congratulations... for doing something like this with template
metaprogramming requires a lot of skill!
|
Thanks.
| Quote: | I've already done something similar before (but using fixed point
arithmetic), and I came to the conclusion that it is better to just use
a "code generator" to do the convolution and generate the static data
in a header!
The reason for this is that:
- the "metaprogram" (i.e, the code-generating program in this case) is
clearer than a templated version;
- debugging and modifying it is simpler;
- compilation time is *way* faster =)
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Indeed, the thought had occured to me (whilst waiting for the compiler to
finish...). But it _feels_ more elegant to do it all in C++ :-)
Maybe one day, everyone will fix their implementation of the template
language, so that it is on a par with other functional languages in terms
of speed.
Ah and don't forget the hand generated code (or code made by a generator
if you like) is 1% slower!
-Ed
--
(You can't go wrong with psycho-rats.) (er258)(@)(eng.cam)(.ac.uk)
/d{def}def/f{/Times findfont s scalefont setfont}d/s{10}d/r{roll}d f 5/m
{moveto}d -1 r 230 350 m 0 1 179{1 index show 88 rotate 4 mul 0 rmoveto}
for /s 15 d f pop 240 420 m 0 1 3 { 4 2 1 r sub -1 r show } for showpage
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
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