CORDIC算法的matlab实现

大笨象

不知道有木有人研究这个，比较偏向于硬件描述。
+ Z" H) M0 n, x+ V% M今天先发一个sine cose函数的实现。
8 D* I# k$ N5 B' V+ ]有兴趣的可以看一下，m文件见附件。
function v=f_cordic(beta,n)
! A$ E* u% J( A6 W' gif beta < -pi/2 || beta > pi/2
7 S$ q+ Q; d0 V* \8 K( e    if beta < 0
        v=f_cordic(beta + pi,n);
    else
        v=f_cordic(beta - pi,n);
. P, q/ j2 x6 a    end
    v = -v;% flip the sign for second or third quadrant
    return
end
% Initialization of tables of constants used by CORDIC
$ E- t- s$ @2 S- V6 W% need a table of arctangents of negative powers of two, in radians:
% angles = atan(2.^-(0:27));
angles =  [  ...
' r. c9 K' H% H) M    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
+ D& Y, P# U3 d# z1 U* o    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
$ {0 o! W2 Q( S' `5 y! l    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
  x/ R6 G5 Q3 W' _: M$ O7 y    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
' {9 N$ p' A0 o2 p' ~/ F2 P- _% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
Kvalues = [ ...
! J; |4 ?* B* P4 i7 |' A    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
5 b( U: F8 ?/ H& s. @/ O    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
) X& G& T% L6 T" q; m7 B9 ?% i    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
% E: h' }4 g+ T5 M    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
Kn = Kvalues(min(n, length(Kvalues)));
4 S8 m/ `( @5 d7 J
% Initialize loop variables:
v = [1;0]; % start with 2-vector cosine and sine of zero
# [5 c" x$ `% N  N) m/ Opoweroftwo = 1;
% Iterations
' ]1 W. w9 t4 Z2 f7 bfor j = 1:n;
    if beta < 0
        sigma = -1;
1 K5 X; z) y! h    else
% [: j. e5 V' T        sigma = 1;
    end
' `' C6 C8 Q9 S: q6 q    % update the angle from table, or eventually by just dividing by two
1 i6 V4 G8 Y/ B4 u8 [    if j <= length(angles)
        angle = angles(j);
    else
        angle = angle/2;
0 n, f: ?& A2 N# q    end
    factor = sigma * poweroftwo;
2 I" ~. ?$ Z- R; X    R = [1, -factor; factor, 1];
    v = R * v; % 2-by-2 mtrix multiply
    beta = beta - sigma * angle; % update the remaining angle
- t! |8 b1 _' e& g! I3 @, _    poweroftwo = poweroftwo / 2;
end
% Adjust length of output vector to be [cos(beta), sin(beta)]:
& I9 Q3 z& ]* {v = v * Kn;
( \# k4 j* H2 \! Treturn
0 u& g% T7 k: u8 U, i+ i( X- ~+ V
使用20位寄存器，仿真波形如下：

杨帆

我表示学习了

zhangjichang

这是什么算法？第一次听说

赛才

我表示很给力

大笨象

zhangjichang 发表于 2011-6-8 22:31
4 v) R8 m. W1 k$ K9 J5 r; N这是什么算法？第一次听说

) w$ ^& w5 f( z  K. |) t这个，就是那个。感兴趣的话你还是自己搜搜吧。

大笨象

赛才 发表于 2011-6-9 15:01
, P4 `3 k2 `0 w7 C5 H我表示很给力

给力就好。呵呵

魅影骑士

顶一下！

yingzhen

费解。。。。。。。。。。。。。。。。

羅雲琦

有什麽用？求解

jt202010