CORDIC算法的matlab实现

大笨象

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/ v, C2 n4 q2 s3 Y5 t不知道有木有人研究这个，比较偏向于硬件描述。
今天先发一个sine cose函数的实现。
有兴趣的可以看一下，m文件见附件。
' x, n8 `: h; ]1 Ofunction v=f_cordic(beta,n)
if beta < -pi/2 || beta > pi/2
. i8 F/ f' E# e1 S: I8 s+ C    if beta < 0
3 m9 U' x0 Z) S1 S        v=f_cordic(beta + pi,n);
    else
8 j+ Z3 ]# E# ^' V        v=f_cordic(beta - pi,n);
3 @1 h3 F) @" ^, H% _8 X$ t+ {    end
; t6 r0 _& }2 X1 z    v = -v;% flip the sign for second or third quadrant
    return
end
% Initialization of tables of constants used by CORDIC
% need a table of arctangents of negative powers of two, in radians:
+ b1 X' }. P  e7 C+ g% angles = atan(2.^-(0:27));
6 E: C) R  I# T  xangles =  [  ...
    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
5 I; ?5 t/ O2 e  M( h5 ~    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
7 E# O" _+ E# L9 e    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
* D' [6 G* c1 Z: G    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
1 w7 [$ _; C0 @+ T) L* }" `) `- e    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
9 p4 A2 F1 Z% j, [- R3 w    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
' B& L* E; ~" i: R3 }% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
. L6 P* f4 a+ ^0 e% r7 {Kvalues = [ ...
    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
& @/ f5 Z+ b! a% p  R6 ^    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
" U6 Q7 w3 Z0 ~0 ]4 _7 u" f( M    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
/ }/ t' s4 e3 K    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
" D5 J, ]' `' o- T- \Kn = Kvalues(min(n, length(Kvalues)));
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% Initialize loop variables:
v = [1;0]; % start with 2-vector cosine and sine of zero
/ R# B: O$ `% _7 k! C0 Tpoweroftwo = 1;
5 k# ^' A7 q2 h1 v8 N) g% Iterations
for j = 1:n;
    if beta < 0
        sigma = -1;
8 D2 }, o. g4 t$ t    else
        sigma = 1;
    end
+ C0 B3 D+ t# v0 L  ]: I; L    % update the angle from table, or eventually by just dividing by two
    if j <= length(angles)
0 p0 s  ?* N! @/ z; D        angle = angles(j);
    else
        angle = angle/2;
    end
2 ^$ |: ^! F, V! c" b  N+ Y. I    factor = sigma * poweroftwo;
0 j) s) J* y8 R; ?    R = [1, -factor; factor, 1];
+ q' O9 B$ J: d  v( w7 N! ]    v = R * v; % 2-by-2 mtrix multiply
' p0 _! U  Q* p( m7 V& ?    beta = beta - sigma * angle; % update the remaining angle
3 [4 x" f6 b" h; x+ l( W    poweroftwo = poweroftwo / 2;
end
+ M" K! K+ L& B) |9 D$ `) Q9 c% Adjust length of output vector to be [cos(beta), sin(beta)]:
v = v * Kn;
  ~; m; |; y% Q8 `9 Ureturn
$ q$ p5 ?0 t5 L  A  P3 ~5 i6 [- b
使用20位寄存器，仿真波形如下：

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2740419624

挺好的，作者台历好了怎么龙牙

Lsiten

顶顶顶一下

Arbitrary1111

thanks for giving

sdccumcm

好的 学习一下！           

大笨象

羅雲琦 发表于 2011-6-9 22:32
* l/ x- y4 d2 z# [$ e; ^: {有什麽用？求解

; U# D4 j  n- X7 @; j可以使用硬件实现啊。使用加法器和移位寄存器就可以计算三角函数。

沉默到底

路过。。。。。

沉默到底

路过。。。

晨宸

表示看不懂