CORDIC算法的matlab实现

大笨象

( }# e+ Z5 E8 {3 H8 d7 J" _- v
不知道有木有人研究这个，比较偏向于硬件描述。
8 p6 F4 c+ `& r+ q5 @3 T2 }3 b+ U) n今天先发一个sine cose函数的实现。
有兴趣的可以看一下，m文件见附件。
# I/ v- q% C2 t' ^1 ffunction v=f_cordic(beta,n)
' q3 q/ ^! z5 {8 P. n) ?4 vif beta < -pi/2 || beta > pi/2
4 S2 Q9 u. K5 a5 i& ?    if beta < 0
        v=f_cordic(beta + pi,n);
# N. p4 m: R- J2 B    else
" w: n! a( s# D2 X' ^/ ~. _        v=f_cordic(beta - pi,n);
    end
    v = -v;% flip the sign for second or third quadrant
    return
' B! J1 R  u% l3 d9 h& [* ?end
% Initialization of tables of constants used by CORDIC
) l9 G% p4 J! p& M, s2 y% need a table of arctangents of negative powers of two, in radians:
* V2 a$ t- b4 Y9 O% angles = atan(2.^-(0:27));
angles =  [  ...
    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
1 w& e! G8 n0 E1 I) P1 F1 s  D' a    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 ...
    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
9 g3 E2 o5 t( X4 `$ T9 ?Kvalues = [ ...
: w  t) A* {2 K7 E" _- K5 B- f    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
. Q' U' W! Q+ Q, k    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
& X6 n3 n9 ~, l& {0 |: ]    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
) h! M3 z5 ~- P- F# p3 cKn = Kvalues(min(n, length(Kvalues)));

* q  t2 |6 F: O% Initialize loop variables:
v = [1;0]; % start with 2-vector cosine and sine of zero
/ {1 Q! K5 d% T7 c( w  y$ B& l* npoweroftwo = 1;
% Iterations
for j = 1:n;
% Q. T1 i" a8 }    if beta < 0
        sigma = -1;
) O& K8 ?. O8 q+ |( g    else
        sigma = 1;
    end
* I/ M8 D6 Y8 G/ M0 l3 U( I    % update the angle from table, or eventually by just dividing by two
: E3 _% R! ~9 n. s$ ]    if j <= length(angles)
        angle = angles(j);
9 U* L: b; ?9 j% h" s. K( ?3 T    else
# a0 }3 b% G) p        angle = angle/2;
    end
( _1 ?7 N: n4 g1 b2 m6 A    factor = sigma * poweroftwo;
    R = [1, -factor; factor, 1];
    v = R * v; % 2-by-2 mtrix multiply
    beta = beta - sigma * angle; % update the remaining angle
    poweroftwo = poweroftwo / 2;
7 K" B5 _1 G) Lend
% Adjust length of output vector to be [cos(beta), sin(beta)]:
v = v * Kn;
7 m1 a) S5 c  m) x7 Yreturn
& d4 {8 n4 ^) s; A
3 O8 s  `! _& @6 A0 N使用20位寄存器，仿真波形如下：

: X; P* l3 Z# n% ?+ `" c

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
( N8 B+ C- q4 o- L6 n这是什么算法？第一次听说

+ o6 A3 ?$ ]* Z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
, Z" B' H2 C- h: 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