Linprog: No feasible solution found.

clc ; 
clear all ; 
close all ;

% N = input('Tell me the length N: '  );
N = 25;

K = N + 1 ;

w4 = linspace( 0 , pi , 10*K  );
idx = (w4 > 0.4*pi) & (w4 < 0.5*pi );
w4(idx) = [];

w4 = sort(w4);
w4 = w4';

D1= ones( 2*length(w4),1);
W1= ones( 2*length(w4),1);
for i = 1:1:length(w4)
    if w4(i)>= 0.4*pi
        h = 2*i;
        break;
    end
end
for i = 2:2:length(w4)
    D1(i)= -1;
end
for h = h:length(D1)
    D1(h)= 0;
    W1(h) = 2;
end
for i = 2:2:2*length(w4)
    W1(i)= -1*W1(i);
end

y1 = zeros( length(D1) , K+1);

for i = 1:1:length(w4)
    for j = 1:1:K+1
        y1(2*i-1,j) = 2*cos((j-1)*w4(i));
        y1(2*i-1,1) = 1;
        y1(2*i,j) = -2*cos((j-1)*w4(i));
        y1(2*i,1) = -1;
        y1(2*i-1,K+1) = 1/W1(2*i);
        y1(2*i,K+1) = -1/W1(2*i);
    end
end

f = zeros( 1,K+1);
f(:,K+1)=1;
y2 = zeros( 1 , K+1);
for i = 1:1:K+1
    y2(i)=2*cos((i-1)*0.45*pi);
    y2(1) = 1;
    y2(K+1) = 0;
end
d1 = 0.5;
X= linprog(f,y1,D1,y2,d1);

I have these arrays for inequality ( yi , D1 ) and this for equality ( y2 , d1 ) and the (f) from x*f'.

What am i doing wrong with the linprog command?