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。
9 W; q/ U" O' K4 G# J' m今天先发一个sine cose函数的实现。
6 d8 ~# V) |' D  R$ q4 p有兴趣的可以看一下，m文件见附件。
, h. l% S/ U% `8 afunction v=f_cordic(beta,n)
if beta < -pi/2 || beta > pi/2
    if beta < 0
4 i5 ?: S1 q2 l1 }        v=f_cordic(beta + pi,n);
  ~) A$ W) L+ S( k% A4 J    else
        v=f_cordic(beta - pi,n);
    end
    v = -v;% flip the sign for second or third quadrant
3 E; Q- _; C$ Z    return
end
% Initialization of tables of constants used by CORDIC
: a4 _( L" i2 f9 {0 l' e9 o8 U% need a table of arctangents of negative powers of two, in radians:
% angles = atan(2.^-(0:27));
angles =  [  ...
- C! _! |; d! k1 S3 Y7 q! E& Y    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
5 A  k) M8 R% A9 I) Q    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
! e! d7 R4 L; [- B0 X% P& b    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
0 X  C6 O* c( D, \' y/ |    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
' S' a, \1 p( I1 X: B0 O% i    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
0 {: I' V% p" G% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
& u7 Y, m1 G2 N2 ~% s, \# P) N/ qKvalues = [ ...
    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
; W' T- Y6 _+ U; u    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
8 J5 K5 {8 ?  [    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
1 K% w3 A7 q2 r8 C' G; ~    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
" f/ H5 B% O8 L0 h$ Z& Y    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
9 S6 R7 m; E( q6 C/ oKn = Kvalues(min(n, length(Kvalues)));
* Z4 v, E2 g- U0 H# X
% Initialize loop variables:
+ I" i5 k0 g% H. V# mv = [1;0]; % start with 2-vector cosine and sine of zero
poweroftwo = 1;
% Iterations
. X) {+ ^, e- r" U6 g# k8 |for j = 1:n;
    if beta < 0
        sigma = -1;
    else
) B* z  z5 V, z) ~, t! U        sigma = 1;
    end
1 R1 l# b6 I# o1 n' `( I: K    % update the angle from table, or eventually by just dividing by two
    if j <= length(angles)
        angle = angles(j);
    else
- J& Q: {2 _! z* M        angle = angle/2;
# O; J' s- N1 `% g8 ^( s    end
    factor = sigma * poweroftwo;
/ c3 b6 [3 _4 ?9 P# N: [$ n% @: ~    R = [1, -factor; factor, 1];
    v = R * v; % 2-by-2 mtrix multiply
    beta = beta - sigma * angle; % update the remaining angle
, p* A; _1 z, R: F+ n    poweroftwo = poweroftwo / 2;
end
& k- _$ J) Z- m% Adjust length of output vector to be [cos(beta), sin(beta)]:
v = v * Kn;
return

5 J2 r* H, m: Z, B6 o; u使用20位寄存器，仿真波形如下：

2740419624

挺好的，作者台历好了怎么龙牙
# ?9 H: n4 @  U% a1 V: d

Lsiten

顶顶顶一下
+ I/ X. c6 L' B! c. g; A. i

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
% |$ @9 E* {0 v% I  ^7 z有什麽用？求解

0 c9 }- t8 e% w0 l8 }' f3 y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