Talk:CORDIC

message: The article mixes in n and i for subscripts and superscripts and it is confusing. n should be used to refer to the total number of iterations while i should refer to the current iteration. This pops up in the beta(n+1) equation. I don't know if I am right so I am hesitant to change it. Maybe someone with a little more experience w/the algorithm can edit it. Addps4cat 20:01, 3 March 2006 (UTC)
replies: text: *takes a second look at what actually is written*. Hm. You are absolutely correct, it is very unclear and confusing right now. If no one else beats me to it, I'll fix it tomorrow. Henrik 01:59, 4 March 2006 (UTC)
thread_title: Mixing i and n

message: Somebody has written: "For most ordinary purposes, 40 iterations (n = 40) is sufficient to obtain the correct result to the 10th decimal place."
Actually the number of iterations for CORDIC  must be equal to the wordlength. For example, if the wordlength is 16 there is no sense to do 40 iterations , as said unknown author. In this case the number of iterations must be 16. Not more and not less!  —Preceding unsigned comment added by Vladimir Baikov (talk • contribs) 08:28, 22 November 2007 (UTC)
thread_title: Strange statement

message: any idea of the accuracy of this algorithm and connections with the number of iterations ?
any comparison between this algorithm an some others ?
--bloublou 10:58, 11 August 2006 (UTC)
thread_title: accuracy

message: The python code above seems a little complex given that a port of the C implementation
to JS can be written like this:
var AG_CONST = 0.6072529350;
 
function FIXED(X)
{
  return X * 65536.0;
}
 
function FLOAT(X)
{
  return X / 65536.0;
}
 
function DEG2RAD(X)
{
  return 0.017453 * (X);
}
 
var Angles = [
  FIXED(45.0), FIXED(26.565), FIXED(14.0362), FIXED(7.12502),
  FIXED(3.57633), FIXED(1.78991), FIXED(0.895174), FIXED(0.447614),
  FIXED(0.223811), FIXED(0.111906), FIXED(0.055953),
  FIXED(0.027977) 
	      ];
 
var X;
var Y;
var TargetAngle;
var CurrAngle;
var Step;
 
X = FIXED(AG_CONST);         /* AG_CONST * cos(0) */
Y = 0;                       /* AG_CONST * sin(0) */
 
TargetAngle = FIXED(28.027);
CurrAngle = 0;
for (Step = 0; Step < 12; Step++) {
    var NewX;
    if (TargetAngle > CurrAngle) {
      NewX = X - (Y >> Step);
      Y = (X >> Step) + Y;
      X = NewX;
      CurrAngle += Angles[Step];
    } else {
      NewX = X + (Y >> Step);
      Y = -(X >> Step) + Y;
      X = NewX;
      CurrAngle -= Angles[Step];
    }
}
 
print('CORDIC: ' + FLOAT(TargetAngle) + ' ' + FLOAT(Y) + ' ' + FLOAT(X) + '\n' );
print('FP: ' + FLOAT(TargetAngle) + ' ' + Math.sin(DEG2RAD(FLOAT(TargetAngle))) + ' ' + Math.cos(DEG2RAD(FLOAT(TargetAngle))) + '\n' );
86.152.208.199 00:55, 19 February 2007 (UTC)
thread_title: JavaScript

message: It would be much more logical to put  the References 
in the chronological order: 
beginning from the first publications to the recent ones. —The preceding unsigned comment was added by 80.133.27.236 (talk) 21:37, 12 January 2007 (UTC)
replies: text: I disagree.  Let them come in the order that they are referred to, like most wikipedia articles do. Dicklyon 01:36, 13 January 2007 (UTC)

text: K = \lim_{n \to \infty}K(n) \approx 0.6072529350088812561694 . 
The number of iterations n should be equal the wordlength of the computer. Unlimited n corresponds to  unlimited wordlength. Did anybody see a computer with the unlimited  length of word?! 
On the other hand,  if the number of iterations is, for example, 32, then the value of K should  be necessary to evaluate just for n=32. If instead of that we use suggested K=0.6072529350088812561694 (for :  \_{n \to \infty}) then error would be large!
In the other words the coefficient K for unlimited n has neither practical nor theoretical sense! 
So reference number [3] is unnecessary.  Vladimir Baykov (talk) 21:25, 18 July 2010 (UTC)
thread_title: References

message: About the following edit:
01:00, 2 January 2007 Dicklyon (Talk | contribs) (→Implementation in C - remove section, as the algorithm is not useful either pedagogically or practically in this form)
C is more known than MATLAB. Please allow the example at least here. Thanks. :) 130.83.161.82 08:39, 18 May 2007 (UTC)
thread_title:  Implementation in C 

message: I don`t understand what is the difference between NOTES and REFERENCES?
I guess it would be better ALL LITERATURE state in the chronological order!  — Preceding unsigned comment added by 134.99.136.28 (talk) 13:41, 12 October 2013 (UTC)
replies: text: The distinction is not universally followed, but ideally Notes are clarifications and References are sources. —Tamfang (talk) 23:48, 12 October 2013 (UTC)
thread_title:  What is the difference between NOTES and REFERENCES? 

message: The Motorola 68000 Floating Point Coprocessor, the MC68881, internally uses CORDIC. The MC68882 does as well and improves on its predecessor by generating a result step on each clock edge (doubling the speed).
I think the 6809's Floating Point ROM M6839 also uses CORDIC as it was developed by the same engineers, before they worked on the 68000's co-processor.  — Preceding unsigned comment added by 131.107.147.56 (talk) 20:28, 8 October 2014 (UTC)
replies: text: Of course, this can be included, but we need reliable references. --Matthiaspaul (talk) 01:06, 4 January 2016 (UTC)
thread_title:  (Co)Processors using Cordic 

message: Hello fellow Wikipedians,
I have just modified 5 external links on CORDIC. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
*Added archive https://web.archive.org/web/20150309055201/http://www.jacques-laporte.org/Briggs%20and%20the%20HP35.htm to http://www.jacques-laporte.org/Briggs%20and%20the%20HP35.htm
*Added archive https://web.archive.org/web/20150309055210/http://www.jacques-laporte.org/Trigonometry.htm to http://www.jacques-laporte.org//Trigonometry.htm
*Added archive https://web.archive.org/web/20160818122704/http://www.jacques-laporte.org/TheSecretOfTheAlgorithms.htm to http://www.jacques-laporte.org/TheSecretOfTheAlgorithms.htm
*Added archive https://web.archive.org/web/20160818121038/http://www.jacques-laporte.org/digit_by_digit.htm to http://www.jacques-laporte.org/digit_by_digit.htm
*Added archive https://web.archive.org/web/20160818120118/http://www.jacques-laporte.org/Logarithm_1.htm to http://www.jacques-laporte.org/Logarithm_1.htm
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
Cheers.—InternetArchiveBot (Report bug) 17:50, 28 July 2017 (UTC)
thread_title:  External links modified 

message: CORDIC 
* and closely related methods 
** known as:
:::* pseudo-multiplication 
::* and 
::::* pseudo-division 
:::* or 
::::* factor combining 
* are commonly used 
** when no hardware multiplier is available 
*** (e.g. in simple microcontrollers and FPGAs).
** as the only operations it requires are
*** additions, subtractions, bitshift and lookup tables.
:
As such, they all belong to the class of shift-and-add algorithms.
:
In computer science, CORDIC is often used to implement floating-point arithmetic when the target platform lacks hardware multiply for cost or space reasons.
I just added the last sentence quoted above. It partially duplicates the first sentence above (grammatically exploded), but 95% of readers will barely notice this, as their parse recursion is already busy dropping the factoids embedded in the first sentence into the buffer-overrun bit bucket. — MaxEnt 13:25, 3 September 2020 (UTC)
thread_title:  Bury the lede 

message: The More Formalized section of this article uses sin and cos in the rotation matrix to develop the ability to calculate sin and cos. 174.63.44.188 (talk) 02:28, 17 March 2023 (UTC)
replies: text: oh nvm I didn't read the bitshift implementation >.< 174.63.44.188 (talk) 02:34, 17 March 2023 (UTC)
thread_title:  More Formalized can't be the algorithm