沃尔什-哈达玛变换

%快速沃尔什变换程序

function xx=fwhtdya2d(data2);

xx=data2;

N=length(xx);

for i=1:N;

xx1(i,:)=fwhtdya1d(xx(i,:));

end

xx=zeros(N);

for j=1:N;

xx(:,j)=fwhtdya1d(xx1(:,j)')';

end

function x=fwhtdya1d(data1);

N=length(data1);

L=log2(N);

k1=N;k2=1;k3=N/2;

for i1=1:L

L1=1;

for i2=1:k2;

for i3=1:k3;

i=i3+L1-1;j=i+k3;

temp1=x(i);temp=x(j);

x(i)=temp1+temp2;

x(j)=temp1-temp2;

end

L1=L1+K1;

end

k1=k1/2;k2=k2*2;

k3=k3/2;

end

x=inv(N)*x;