implementing pre-whitening learning rule.

i am applying pre-whitening in my project and my loop is going infinite.I am applying learning rule. kindly help me. My code is:

clc; clear all; i1=imread('t1.jpg'); i2=rgb2gray(i1); p=imresize(i2,[128 128]); p1=reshape(p,1,16384); subplot(4,4,1) imshow(p); k1=kurtosis(double(p1(:))); i3=imread('t2.jpg'); i4=rgb2gray(i3); q=imresize(i4,[128 128]); q1=reshape(q,1,16384); subplot(4,4,2) imshow(q); k2=kurtosis(double(q1(:))); i5=imread('t3.jpg'); i6=rgb2gray(i5); s=imresize(i6,[128 128]); s1=reshape(s,1,16384); subplot(4,4,3) imshow(s); k3=kurtosis(double(s1(:))); c=rand(3,3); subplot(4,4,4) imshow(c) k3=kurtosis(double(c(:))); k=[k1 k2 k3]; s2=[p1; q1; s1]; a=5; b=10; a1=unifrnd(a,b,3,3); x=a1*double(s2); y=c*x; z=c*y; t1=z(1,:); t2=z(2,:); t3=z(3,:); y1=reshape(t1,128,128); y2=reshape(t2,128,128); y3=reshape(t3,128,128); %colormap(gray) subplot(4,4,5) imagesc(y1); subplot(4,4,6) imagesc(y2); subplot(4,4,7) imagesc(y3); v2=rand(3,3); % from here the code is of pre-whitening. v=v2*z I=[1,0,0;0,1,0;0,0,1]; % while (cov(v*v')~=I) % V=V+0.5*[I-(v*v')]; % v=V*z; % end % c=cov(v*v'); t=1; while(c~=I) v=v2+0.5*[I-(v*v')] v=v*z c=v*v'; end v=v1*z