For implementation on DSP processors, I always prefer polynomial
approximation. Did anybody implemented using spline method? I came to
know that it gives better accuracy.

Anandh

george.w.bush@whitehouse.com (George Bush) wrote in message news:<%GnVc.8231$Bt5.4288@twister.socal.rr.com>...
> For hardware implementations, you might look at CORDIC.  CORDIC wouldn't work 
> well for general purpose or DSPs.
> 
> In article <2f592dd3.0408200028.21978843@posting.google.com>, 
> akd_ecc@yahoo.com (EC-AKD) wrote:
> >Hi,
> >
> > I am looking for some good fixed point algorithms for logarithms and
> >exponents. Any pointers would be helpful.
> >
> >Thanks and Regards,
> >-Anoop Deoras

Where do you think binary weights come from?

In article <sxdvff53nel.fsf@edgedsp4.rtp.ericsson.se>, Raymond Toy 
<raymond.toy@ericsson.com> wrote:
>>>>>> "George" == George Bush <george.w.bush@whitehouse.com> writes:
>
>    George> Sounds pretty much the same except mine had some jumps.  Do a cycle
> count and 
>    George> compare the number of cycles with the normal implementation.  It's
> worse with 
>    George> a pipelined processor.
>
>Well, yes of course.  But you said bit operations.  I don't consider a
>branch a bit operation.  
>
>But, yes, branches hurt on pipelined processors, especially since you
>probably can't predict the branch in a CORDIC routine.
>
>Ray

>>>>> "George" == George Bush <george.w.bush@whitehouse.com> writes:

    George> Sounds pretty much the same except mine had some jumps.  Do a cycle count and 
    George> compare the number of cycles with the normal implementation.  It's worse with 
    George> a pipelined processor.

Well, yes of course.  But you said bit operations.  I don't consider a
branch a bit operation.  

But, yes, branches hurt on pipelined processors, especially since you
probably can't predict the branch in a CORDIC routine.

Ray

Sounds pretty much the same except mine had some jumps.  Do a cycle count and 
compare the number of cycles with the normal implementation.  It's worse with 
a pipelined processor.

In article <sxd4qmr402e.fsf@edgedsp4.rtp.ericsson.se>, Raymond Toy 
<raymond.toy@ericsson.com> wrote:
>>>>>> "George" == George Bush <george.w.bush@whitehouse.com> writes:
>
>    George> CORDIC uses bit operations which aren't effecient in general
> purpose 
>    George> operations.
>
>Your CORDIC must be different from mine.  All I had were compares,
>adds, subtracts, shifts, and table lookups.  Sounds pretty general
>purpose to me.
>
>Ray

"Dirk Bell" <dirkman@erols.com> wrote in message
news:6721a858.0408251532.725e6170@posting.google.com...
> Cordic for logarithms? Got a reference for that?
>
> Dirk
>

http://www.magic-software.com/Documentation/CordicMethods.pdf

Gives a set of formulas for sin(x), cos(x), atan(x/y),  sinh(x), cosh(x) and
atanh(x/y)

http://www.xilinx.co.jp/products/software/sysgen/app_docs/user_guide_Chapter_10_Section_4_Subsection_25.htm

points out the identity   log (w) = 2 x atanh[(w-1) / (w+1)]

   Best wishes,
   --Phil Martel

> george.w.bush@whitehouse.com (George Bush) wrote in message
news:<%GnVc.8231$Bt5.4288@twister.socal.rr.com>...
> > For hardware implementations, you might look at CORDIC.  CORDIC wouldn't
work
> > well for general purpose or DSPs.
> >
> > In article <2f592dd3.0408200028.21978843@posting.google.com>,
> > akd_ecc@yahoo.com (EC-AKD) wrote:
> > >Hi,
> > >
> > > I am looking for some good fixed point algorithms for logarithms and
> > >exponents. Any pointers would be helpful.
> > >
> > >Thanks and Regards,
> > >-Anoop Deoras

Cordic for logarithms? Got a reference for that?

Dirk

george.w.bush@whitehouse.com (George Bush) wrote in message news:<%GnVc.8231$Bt5.4288@twister.socal.rr.com>...
> For hardware implementations, you might look at CORDIC.  CORDIC wouldn't work 
> well for general purpose or DSPs.
> 
> In article <2f592dd3.0408200028.21978843@posting.google.com>, 
> akd_ecc@yahoo.com (EC-AKD) wrote:
> >Hi,
> >
> > I am looking for some good fixed point algorithms for logarithms and
> >exponents. Any pointers would be helpful.
> >
> >Thanks and Regards,
> >-Anoop Deoras

>>>>> "George" == George Bush <george.w.bush@whitehouse.com> writes:

    George> CORDIC uses bit operations which aren't effecient in general purpose 
    George> operations.

Your CORDIC must be different from mine.  All I had were compares,
adds, subtracts, shifts, and table lookups.  Sounds pretty general
purpose to me.

Ray

CORDIC uses bit operations which aren't effecient in general purpose 
operations.

In article <sxdr7pw615c.fsf@edgedsp4.rtp.ericsson.se>, Raymond Toy 
<raymond.toy@ericsson.com> wrote:
>>>>>> "George" == George Bush <george.w.bush@whitehouse.com> writes:
>
>    George> For hardware implementations, you might look at CORDIC.  CORDIC
> wouldn't work 
>    George> well for general purpose or DSPs.
>
>Why not?
>
>Ray

>>>>> "George" == George Bush <george.w.bush@whitehouse.com> writes:

    George> For hardware implementations, you might look at CORDIC.  CORDIC wouldn't work 
    George> well for general purpose or DSPs.

Why not?

Ray

For hardware implementations, you might look at CORDIC.  CORDIC wouldn't work 
well for general purpose or DSPs.

In article <2f592dd3.0408200028.21978843@posting.google.com>, 
akd_ecc@yahoo.com (EC-AKD) wrote:
>Hi,
>
> I am looking for some good fixed point algorithms for logarithms and
>exponents. Any pointers would be helpful.
>
>Thanks and Regards,
>-Anoop Deoras