CORDIC算法的matlab实现

大笨象

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4 H/ |9 y: l0 p9 H不知道有木有人研究这个，比较偏向于硬件描述。
今天先发一个sine cose函数的实现。
# s1 R- U4 I6 k有兴趣的可以看一下，m文件见附件。
( k7 ~$ B  g: [% P3 tfunction v=f_cordic(beta,n)
8 A+ U6 r, z! T$ K2 Bif beta < -pi/2 || beta > pi/2
    if beta < 0
        v=f_cordic(beta + pi,n);
( E& @- S+ F4 X8 n3 H" N    else
9 U" [, @" B1 S1 |$ e$ F        v=f_cordic(beta - pi,n);
    end
    v = -v;% flip the sign for second or third quadrant
    return
2 g* e2 r1 n7 v  pend
9 x7 U0 g# w) j8 U( P/ U5 G% Initialization of tables of constants used by CORDIC
6 @# `2 l1 M6 P9 d% need a table of arctangents of negative powers of two, in radians:
. H  y, _/ l* S7 \1 \% angles = atan(2.^-(0:27));
angles =  [  ...
    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
. f" M4 _( `% b5 g    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
% F% W* o4 _2 h; H& P% ~! e    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
, B# c8 f- b- D% R; `    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
" x; J) W. q% X3 I    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
  ~0 v: W) V& D" J: |5 I% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
$ h; C6 h$ A& u- B; c. MKvalues = [ ...
; i4 ]8 j( s1 y. c( J. ?* T2 |    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
6 b; ]4 p: ]1 o: @9 r1 t0 W/ R; |    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
2 m! e0 H- G& X% I    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
9 E3 F5 |, t# D, Y# @# ?% D* B    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
Kn = Kvalues(min(n, length(Kvalues)));

! [# \/ B3 I2 b/ Z% Initialize loop variables:
v = [1;0]; % start with 2-vector cosine and sine of zero
( f; r- M# }1 V) h' P* o' Rpoweroftwo = 1;
1 M# E0 z' n3 I. i% Iterations
+ o: h; \3 e3 H1 pfor j = 1:n;
; K" z, ~6 ~$ U% ~% X9 U# `    if beta < 0
        sigma = -1;
: _1 a& x* u  f" B7 |6 B    else
+ P* d3 z$ k7 X9 F2 k$ g        sigma = 1;
    end
    % update the angle from table, or eventually by just dividing by two
    if j <= length(angles)
" p8 e6 |% M4 f" z        angle = angles(j);
7 q+ a% M! b% @, }8 l- s' r8 M  j    else
        angle = angle/2;
" X8 O0 P" c( }4 |    end
    factor = sigma * poweroftwo;
- [) W3 N7 R  F1 m, ~    R = [1, -factor; factor, 1];
7 p' ~, q+ m+ i+ X    v = R * v; % 2-by-2 mtrix multiply
" ~" Y9 L3 S* ~* v. p    beta = beta - sigma * angle; % update the remaining angle
7 p! Z& p# o% n! k3 _    poweroftwo = poweroftwo / 2;
end
% Adjust length of output vector to be [cos(beta), sin(beta)]:
4 T# p# f9 \* |v = v * Kn;
& `7 ^3 d( G  B' j9 i/ hreturn

使用20位寄存器，仿真波形如下：
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2740419624

挺好的，作者台历好了怎么龙牙
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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
4 l" O' C8 Q. d( G$ d; E7 H1 q有什麽用？求解

" c3 O& [. Z3 g# y. E* ^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