creating square wave problem

Hi everyone:

I have problem in simulink. I created sinus signal, it´s amplitude is 1 and freq is 50 Hz. Then I used "user defined function" and write down this code : here u equals sin function. I divided sinus function in 4 parts, as you can see in code. But the output was not as expected. ANY SUGGESTION ? it only gives -0.8

function y = fcn(u)
  y=0;

                         if(0<=u<0.5)
                            y=0.2;
                         end

                         if (0.5<=u<=1)
                         y=0.7;
                         end

                             if (0>=u>-0.5)
                              y=-0.3;
                             end

                         if (-0.5>=u>=-1)
                              y=-0.8;

                         end

                         end

Answer 1

[Mischa Kim]

Use

 if (0<=u && u<0.5)

and accordingly for all the other if statements.