CORDIC算法的matlab实现

大笨象

/ w. @' `5 U0 h: w% A. o不知道有木有人研究这个，比较偏向于硬件描述。
/ {! e- w* P4 s今天先发一个sine cose函数的实现。
* }8 a  O( m# Z( ]9 v+ N, i/ F4 Z有兴趣的可以看一下，m文件见附件。
function v=f_cordic(beta,n)
5 Y+ }' F! \7 m5 G. vif beta < -pi/2 || beta > pi/2
0 H' B3 |( t/ X% H7 J1 O+ E" |    if beta < 0
+ I: V: E* Q6 J9 s8 n- F        v=f_cordic(beta + pi,n);
4 b1 K- w" J8 j  |! @1 e4 U    else
        v=f_cordic(beta - pi,n);
    end
    v = -v;% flip the sign for second or third quadrant
    return
& J, v" F/ G: m$ O1 r. z5 n# w+ Oend
2 S# I# x; Q# s1 y. e- M$ K. W8 p) L  m4 z% Initialization of tables of constants used by CORDIC
% need a table of arctangents of negative powers of two, in radians:
% angles = atan(2.^-(0:27));
angles =  [  ...
* }; L) R5 i6 s" m    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
* j' F5 e, c& a" |: _2 _& l& F& V    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
4 q2 {" n! \% d) h) Y+ p    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
2 j  }: ~9 z- A9 X* ^    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
Kvalues = [ ...
    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
  `# W1 [* ?8 a/ k% n, @% a    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
) v& b2 a; }' W1 j  {+ v9 R! U. w5 }Kn = Kvalues(min(n, length(Kvalues)));

; Y2 T$ l  s. w& ^% j: x% Initialize loop variables:
v = [1;0]; % start with 2-vector cosine and sine of zero
8 j. l* H4 g  t: z$ E3 j) _# fpoweroftwo = 1;
, U: \* v* n7 \+ i2 W8 `, y7 l% Iterations
9 l7 N2 |5 H, U: ?# B( zfor j = 1:n;
    if beta < 0
        sigma = -1;
    else
% I* s; P: A/ v, b- p4 ~* A  ~" f        sigma = 1;
    end
7 i9 g( z) x4 ]" i3 ?$ {! p/ n# W    % update the angle from table, or eventually by just dividing by two
- }3 O3 I, I6 ?7 ~+ ^    if j <= length(angles)
. W1 G; ]3 g8 Y1 O' a- y7 x        angle = angles(j);
    else
" _/ R9 K$ U* Q8 `3 y5 z: t        angle = angle/2;
    end
    factor = sigma * poweroftwo;
    R = [1, -factor; factor, 1];
    v = R * v; % 2-by-2 mtrix multiply
& i* w* S+ Y7 ^6 [8 d    beta = beta - sigma * angle; % update the remaining angle
    poweroftwo = poweroftwo / 2;
/ S4 D7 X' ^7 C5 t3 wend
% Adjust length of output vector to be [cos(beta), sin(beta)]:
3 Y; @& L- U0 s1 T! p3 C. mv = v * Kn;
return

使用20位寄存器，仿真波形如下：
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9 q8 T5 `* y* H5 L4 Z

2740419624

挺好的，作者台历好了怎么龙牙
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Lsiten

顶顶顶一下
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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

$ X! p: j# G0 A+ m3 R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