CORDIC算法的matlab实现

大笨象

9 r7 |/ ?" H, H9 a3 {8 ~不知道有木有人研究这个，比较偏向于硬件描述。
, {; k+ I1 r6 W1 |今天先发一个sine cose函数的实现。
5 v5 ^* m- B# S: H6 X有兴趣的可以看一下，m文件见附件。
6 _+ Y9 M  J* k& V7 _; mfunction v=f_cordic(beta,n)
if beta < -pi/2 || beta > pi/2
2 M) ?( m) [  C8 j8 h4 p+ j    if beta < 0
        v=f_cordic(beta + pi,n);
  w; _# G9 i" k* a, V+ Q    else
        v=f_cordic(beta - pi,n);
    end
3 a* N. F8 o9 n, c# e    v = -v;% flip the sign for second or third quadrant
    return
# o8 Z7 _# J8 D. Send
% Initialization of tables of constants used by CORDIC
% need a table of arctangents of negative powers of two, in radians:
9 g: T/ K% b+ _# S( u% angles = atan(2.^-(0:27));
7 S4 j# t1 ?8 a. K/ H/ Xangles =  [  ...
: M; H& g1 ], m8 J" V    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
7 V/ E; @/ R1 \, d, `1 U8 L  N    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
0 _; _5 Z" ^+ p% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
Kvalues = [ ...
" B: i6 K( U) @    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
4 `7 p- F0 y4 K$ j1 [    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
+ E$ B1 b& E/ ]0 n    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
7 C  d$ i5 f0 O# }$ b    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
Kn = Kvalues(min(n, length(Kvalues)));

7 W2 J! |: Q$ P# h8 F3 J/ J% Initialize loop variables:
, d% a: k9 {. `v = [1;0]; % start with 2-vector cosine and sine of zero
. Z$ x& V2 I' X+ W. s1 `poweroftwo = 1;
% Iterations
) l' _# `( L1 Y& k, Afor j = 1:n;
* B+ X% {7 c6 f3 D, F    if beta < 0
1 r! i' o) \' u+ s& z" d7 f        sigma = -1;
. |* V4 t  e- X) A8 W    else
        sigma = 1;
    end
    % update the angle from table, or eventually by just dividing by two
1 v+ l" J/ ^2 Y8 X( \/ g    if j <= length(angles)
        angle = angles(j);
    else
% {9 g2 ~9 Z3 \( A0 W! r# W        angle = angle/2;
    end
    factor = sigma * poweroftwo;
9 y+ q2 Y! O! @    R = [1, -factor; factor, 1];
    v = R * v; % 2-by-2 mtrix multiply
3 W8 z# \0 B( J" E9 r: ]    beta = beta - sigma * angle; % update the remaining angle
    poweroftwo = poweroftwo / 2;
5 W$ y& c5 |( ^end
% Adjust length of output vector to be [cos(beta), sin(beta)]:
v = v * Kn;
. Z9 b. \- A) F( Nreturn
1 k5 a9 P; }4 a# ?
使用20位寄存器，仿真波形如下：
8 Y" z! B! M. [9 z$ v

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
有什麽用？求解

0 g4 N' {7 Y& ~1 s0 |5 C9 }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