function y = construct( x )%CONSTRUCT Summary of this function goes here%  Detailed explanation goes hered1=x(3,1)+x(3,3);d2=x(3,2)+x(3,4);d3=x(3,1)-x(3,3);d4=x(3,2)-x(3,4);s1=0.5*x(4,1)*(x(1,1)*d1+x(1,2)*d2)+0.5*x(4,2)*(x(1,3)*d3+x(1,4)*d4);s3=0.5*x(4,1)*(x(1,1)*d1+x(1,2)*d2)-0.5*x(4,2)*(x(1,3)*d3+x(1,4)*d4);s2=0.5*x(4,1)*(x(2,1)*d1+x(2,2)*d2)+0.5*x(4,2)*(x(2,3)*d3+x(2,4)*d4);s4=0.5*x(4,1)*(x(2,1)*d1+x(2,2)*d2)-0.5*x(4,2)*(x(2,3)*d3+x(2,4)*d4);a1=cat(2,s1,-ctranspose(s2));a2=cat(2,s2,ctranspose(s1));b1=cat(2,s3,-ctranspose(s4));b2=cat(2,s4,ctranspose(s3));c1=cat(1,a1,a2);c2=cat(1,b1,b2);e1=cat(2,c1,c2);e2=cat(2,c2,c1);y=cat(1,e1,e2);