clear
h=0.00276;cd=6100;cs=3300;
for w=1000:1000:2000000;
    i=1;j=1;
for c=100:100:9000
b=w/c;
kdt=sqrt(abs((w/cd)^2-b^2));
kst=sqrt(abs((w/cs)^2-b^2));
y1(i)=(kst^2-b^2)^2*tan(kst*h/2);
y2(i)=4*b^2*kst*kdt*tan(kdt*h/2);
 if abs(y1(i)+y2(i))<=0.000001
   y(w/1000,j)=c;
   j=j+1;
 end
   i=i+1;
end
end