Algorithm for x/63 and x/127

Nikolaos Kavvadias <nikolaos.kavvadias@gmail.com> wrote:

>> Sorry to burst your bubble, but that optimization technique has been 
>> around sind effectively forever; 
 
> Bubble == totally burst. However I still don't have a concrete 
> example that the specific expression has been in use. Any 
> specific reference is much appreciated!

In the days before computers had hardware divide, such might have
been well known. 

Related, you might look at:

http://ipnpr.jpl.nasa.gov/progress_report/42-119/119M.pdf

The problem is how to do a cosine transform based image compression
on a machine without hardware multiply. They optimize the transform
coefficients to minimize the 1's, so less shift and add.
(The RCA CDP1802, from about 1976.)

The inverse transform is more complicated, but can be done one
faster ground-based computers.

-- glen