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。
$ {8 S6 _8 I% L% d6 k. V# U今天先发一个sine cose函数的实现。
5 A$ ?7 O8 c9 ^( @, E" K; X. C有兴趣的可以看一下，m文件见附件。
function v=f_cordic(beta,n)
( g, x# @7 ]8 X! `if beta < -pi/2 || beta > pi/2
2 Q% k, I: R; O3 ~    if beta < 0
! P& O. d0 f5 k5 l        v=f_cordic(beta + pi,n);
    else
/ a0 K* }0 D/ c        v=f_cordic(beta - pi,n);
    end
    v = -v;% flip the sign for second or third quadrant
* |% H" X' b5 q; i( g- m    return
end
& I- F- e; F- K0 y/ i; _0 s% Initialization of tables of constants used by CORDIC
" @- }6 b( p6 ^! H% need a table of arctangents of negative powers of two, in radians:
% angles = atan(2.^-(0:27));
. U$ [8 Z. o. ?6 n2 w! t- q6 oangles =  [  ...
1 l5 M& g& a2 F% F    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
% s6 q) y; u1 H6 j, y% F: Q    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
7 j1 s1 Z1 [/ i  H' x* B( M4 y* p: v    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
) S% t5 w# h* {/ f% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
- i8 Z7 M, T, jKvalues = [ ...
    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
) H; k+ ]) o% m) V" H    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
( i& Q: g7 {4 n& M! ^% m    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
( I- N# D4 X4 r6 y* S1 h( x    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
Kn = Kvalues(min(n, length(Kvalues)));
  y1 g* Z  P$ V" {. `) F
' i0 k8 L! b/ a, B% Initialize loop variables:
v = [1;0]; % start with 2-vector cosine and sine of zero
0 q* x- n% a" t! U7 n- xpoweroftwo = 1;
% Iterations
7 n" V0 o- \& w. W* vfor j = 1:n;
    if beta < 0
        sigma = -1;
    else
        sigma = 1;
- t, w8 l) E  S+ p. K6 o$ T. w  W3 J    end
    % update the angle from table, or eventually by just dividing by two
9 `" {4 U4 `# M9 g/ _    if j <= length(angles)
* X) I# @) Q3 r( |. }3 x1 J6 m        angle = angles(j);
    else
9 J) [% k! V# m        angle = angle/2;
    end
5 o4 j3 o- z6 G% a  ]) p5 E! c* ~# O' M    factor = sigma * poweroftwo;
; K' p. d. t: @) G; X: }9 I    R = [1, -factor; factor, 1];
  H$ j' i- V4 Q" D( T7 ~    v = R * v; % 2-by-2 mtrix multiply
/ S' a8 E. o5 o7 a2 C* Z9 Q: l  I! D    beta = beta - sigma * angle; % update the remaining angle
    poweroftwo = poweroftwo / 2;
end
, @2 ^. y# I- `% p% Adjust length of output vector to be [cos(beta), sin(beta)]:
9 w) K7 h; x2 E6 c2 `# A- _- sv = v * Kn;
+ i6 v+ n6 G! i8 @9 ]1 t. _8 Ireturn
5 h7 U8 }- q* s: u0 p2 |
使用20位寄存器，仿真波形如下：

6 x0 a. x3 r) ]

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
这是什么算法？第一次听说

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
- c/ O8 |7 _' M* i$ u; @9 \我表示很给力

- A9 n( B4 I6 d; Z: B* U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