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shreyassg13@gmail.com
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Registered: ‎02-22-2011

fraction arithmetic

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Hello,

 

I am implementing CORDIC algorithm, in one paper they have used fixed point arithmetic, I wanted to know how to do +,-,*,/ operations in this representaion. is this the best or floating point is better?

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hwneff
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Registered: ‎11-18-2008

to answer your last question about whether to do integer or floating point requires

  a lot more information about what you need and how fast you need to compute

   that which you need.

based, however, on your initial comment about fixed point,  i would suggest you

   should investigate something called "q notation" -- a convention that uses

   integer-ish numbers and functions to operate on "fractions".

NB: the word "convention" -- it is just that: whether the binary digit sequence

   "10000000" is 127 or 1 or 0.5 is all a matter of how one has chosen to look at it.

 

for starters, have a look at wikipedia:

http://en.wikipedia.org/wiki/Q_%28number_format%29

 

once you have the technique, then revisit those cordic papers and, if appropriate,

   revisit your problem to determine the apporpriate values and ranges to be using

   as you apply what you've learned.

 

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bassman59
Historian
Historian
3,744 Views
Registered: ‎02-25-2008

@shreyassg13@gmail.com wrote:

Hello,

 

I am implementing CORDIC algorithm, in one paper they have used fixed point arithmetic, I wanted to know how to do +,-,*,/ operations in this representaion. is this the best or floating point is better?


It depends on your application's requirements.

----------------------------Yes, I do this for a living.
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hwneff
Visitor
Visitor
4,005 Views
Registered: ‎11-18-2008

to answer your last question about whether to do integer or floating point requires

  a lot more information about what you need and how fast you need to compute

   that which you need.

based, however, on your initial comment about fixed point,  i would suggest you

   should investigate something called "q notation" -- a convention that uses

   integer-ish numbers and functions to operate on "fractions".

NB: the word "convention" -- it is just that: whether the binary digit sequence

   "10000000" is 127 or 1 or 0.5 is all a matter of how one has chosen to look at it.

 

for starters, have a look at wikipedia:

http://en.wikipedia.org/wiki/Q_%28number_format%29

 

once you have the technique, then revisit those cordic papers and, if appropriate,

   revisit your problem to determine the apporpriate values and ranges to be using

   as you apply what you've learned.

 

View solution in original post