How to plot this graph?

This is my code i am getting output, but i want to simply this because if i have to change the plotting interval i have to change the code please.... any one help me to plot this graph............

</matlabcentral/answers/uploaded_files/92325/output.png> clc; I=1;

x1= [-30 30];

y1=[30 30];

plot(x1,y1,'Linewidth',3);

hold on;

x2=[-30 30];

y2=[-30 -30];

plot(x2,y2,'Linewidth',3);

hold on;

x3=[30 30];

y3=[-30 30];

plot(x3,y3,'Linewidth',3);

hold on;

x4=[-30 -30];

y4=[-30 30];

plot(x4,y4,'Linewidth',3);

hold on;

xlim([-40, 40]);

ylim([-40, 40]);

pause(1);

    if(I==1);

            x1=-30;

            y1=30;

            pause(1);

            p0=plot(x1,y1,'r*','linewidth',8);

            I=I+1;

    end

    if(I==2);   

            x=-25;

            y=30;

            hold on;

            pause(1);

            p1=plot(x,y,'r*','linewidth',8);

            set(p0,'Visible','off');

            I=I+1;
    end

    if(I==3);

            x1=-20;

            y1=30;

            pause(1);

            p2=plot(x1,y1,'r*','linewidth',8);

            set(p1,'Visible','off');

            I=I+1;
    end

    if(I==4);

            x1=-15;

            y1=30;

            pause(1);

            p3=plot(x1,y1,'r*','linewidth',8);

            set(p2,'Visible','off');

            I=I+1;

         end
    if(I==5);
            x1=-10;
            y1=30;
            pause(1);
            p4=plot(x1,y1,'r*','linewidth',8);

            set(p3,'Visible','off');

            I=I+1;

    end

    if(I==6);

            x1=-5;

            y1=30;

            pause(1);

            p5=plot(x1,y1,'r*','linewidth',8);

            set(p4,'Visible','off');

            I=I+1;
    end

    if(I==7);

            x1=0;

            y1=30;

            pause(1);

            p6=plot(x1,y1,'r*','linewidth',8);

            set(p5,'Visible','off');

            I=I+1;

    end

    if(I==8);

            x1=5;

            y1=30;

            pause(1);

            p7=plot(x1,y1,'r*','linewidth',8);

            set(p6,'Visible','off');

            I=I+1;

    end

    if(I==9);

            x1=10;

            y1=30;

            pause(1);

            p8=plot(x1,y1,'r*','linewidth',8);

            set(p7,'Visible','off');

            I=I+1;
    end

    if(I==10);

            x1=15;

            y1=30;

            pause(1);

            p9=plot(x1,y1,'r*','linewidth',8);

            set(p8,'Visible','off');

            I=I+1;
    end

    if(I==11);

            x1=20;

            y1=30;

            pause(1);

            p10=plot(x1,y1,'r*','linewidth',8);

            set(p9,'Visible','off')

            I=I+1;

    end  

    if(I==12);

            x1=25;

            y1=30;

            pause(1);

            p11=plot(x1,y1,'r*','linewidth',8);

            set(p10,'Visible','off');

            I=I+1;

    end

    if(I==13);

            x1=30;

            y1=30;

            pause(1);

            p12=plot(x1,y1,'r*','linewidth',8);

            set(p11,'Visible','off');

            I=I+1;    

    end

     if (I==14);

            x1=30;

            y1=30;

            p13=plot(x1,y1,'r*','linewidth',8);

            set(p12,'Visible','off'); 

            I=I+1;

     end

    if(I==15);   

            x=30;

            y=25;

            hold on;

            pause(1);

            p14=plot(x,y,'r*','linewidth',8);

            set(p13,'Visible','off');

            I=I+1;

    end

    if(I==16);

            x1=30;

            y1=20;

            pause(1);

            p15=plot(x1,y1,'r*','linewidth',8);

            set(p14,'Visible','off'); 

            I=I+1;

    end

    if(I==17);

            x1=30;

            y1=15;

            pause(1);

            p16=plot(x1,y1,'r*','linewidth',8);

            set(p15,'Visible','off');

            I=I+1;

    end

    if(I==18);

            x1=30;

            y1=10;

            pause(1);

            p17=plot(x1,y1,'r*','linewidth',8);

            set(p16,'Visible','off');

            I=I+1;

    end

    if(I==19);

            x1=30;

            y1=5;

            pause(1);

            p18=plot(x1,y1,'r*','linewidth',8);

            set(p17,'Visible','off');

            I=I+1;

    end

    if(I==20);

            x1=30;

            y1=0;

            pause(1);

            p19=plot(x1,y1,'r*','linewidth',8);

            set(p18,'Visible','off');

            I=I+1;

    end

    if(I==21);

            x1=30;

            y1=-5;

            pause(1);

            p20=plot(x1,y1,'r*','linewidth',8);

            set(p19,'Visible','off')

            I=I+1;

    end

    if(I==22);

            x1=30;

            y1=-10;

            pause(1);

            p21=plot(x1,y1,'r*','linewidth',8);

            set(p20,'Visible','off');

            I=I+1;

    end

    if(I==23);

            x1=30;

            y1=-15;

            pause(1);

            p22=plot(x1,y1,'r*','linewidth',8);

            set(p21,'Visible','off');

            I=I+1;

    end

     if(I==24);

            x1=30;

            y1=-20;

            pause(1);

            p23=plot(x1,y1,'r*','linewidth',8);

            set(p22,'Visible','off')

            I=I+1;

     end

    if(I==25);

            x1=30;

            y1=-25;

            pause(1);

            p24=plot(x1,y1,'r*','linewidth',8);

            set(p23,'Visible','off');

            I=I+1;

    end  

    if(I==26);

            x1=30;

            y1=-30;

            pause(1);

            p25=plot(x1,y1,'r*','linewidth',8);

            set(p24,'Visible','off');

            I=I+1;

    end

    if (I==27);

            x1=30;

            y1=-30;

            p261=plot(x1,y1,'r*','linewidth',8);

            set(p25,'Visible','off');

            I=I+1;
    end

    if (I==28);

            x1=25;

            y1=-30;

            pause(1);

            p26=plot(x1,y1,'r*','linewidth',8);

            set(p261,'Visible','off');

            I=I+1;

    end

    if(I==29);   

            x=20;

            y=-30;

            hold on;

            pause(1);

            p27=plot(x,y,'r*','linewidth',8);

            set(p26,'Visible','off');

            I=I+1;

    end

    if(I==30);

            x1=15;

            y1=-30;

            pause(1);

            p28=plot(x1,y1,'r*','linewidth',8);

            set(p27,'Visible','off'); 

            I=I+1;

    end

    if(I==31);

            x1=10;

            y1=-30;

            pause(1);

            p29=plot(x1,y1,'r*','linewidth',8);

            set(p28,'Visible','off');

            I=I+1;

    end

    if(I==32);

            x1=5;

            y1=-30;

            pause(1);

            p30=plot(x1,y1,'r*','linewidth',8);

            set(p29,'Visible','off');

            I=I+1;

    end

    if(I==33);

            x1=0;

            y1=-30;

            pause(1);

            p31=plot(x1,y1,'r*','linewidth',8);

            set(p30,'Visible','off');

            I=I+1;

    end

    if(I==34);

            x1=-5;

            y1=-30;

            pause(1);

            p32=plot(x1,y1,'r*','linewidth',8);

            set(p31,'Visible','off');

            I=I+1;

    end

    if(I==35);

            x1=-10;

            y1=-30;

            pause(1);

            p33=plot(x1,y1,'r*','linewidth',7);

            set(p32,'Visible','off')

            I=I+1;

    end

    if(I==36);

            x1=-15;

            y1=-30;

            pause(1);

            p34=plot(x1,y1,'r*','linewidth',8);

            set(p33,'Visible','off');

            I=I+1;

    end

    if(I==37);

            x1=-20;

            y1=-30;

            pause(1);

            p35=plot(x1,y1,'r*','linewidth',8);

            set(p34,'Visible','off');

            I=I+1;

    end

     if(I==38);

            x1=-25;

            y1=-30;

            pause(1);

            p36=plot(x1,y1,'r*','linewidth',8);

            set(p35,'Visible','off')

            I=I+1;

     end

    if(I==39);

            x1=-30;

            y1=-30;

            pause(1);

            p37=plot(x1,y1,'r*','linewidth',8);

            set(p36,'Visible','off');

            I=I+1;

    end   

    if(I==40);

            x1=-30;

            y1=-30;

            p38=plot(x1,y1,'r*','linewidth',8);

            set(p37,'Visible','off');

            I=I+1;

    end     

    if (I==41);

            x1=-30;

            y1=-25;

            pause(1);

            p39=plot(x1,y1,'r*','linewidth',8);

            set(p38,'Visible','off');

            I=I+1;  

    end  

    if(I==42);  

            x=-30;

            y=-20;

            hold on;

            pause(1);

            p40=plot(x,y,'r*','linewidth',8);

            set(p39,'Visible','off');

            I=I+1;

    end

    if(I==43);

            x1=-30;

            y1=-15;

            pause(1);

            p41=plot(x1,y1,'r*','linewidth',8);

            set(p40,'Visible','off'); 

            I=I+1;

    end

    if(I==44);

            x1=-30;

            y1=-10;

            pause(1);

            p42=plot(x1,y1,'r*','linewidth',8);

            set(p41,'Visible','off');

            I=I+1;

    end

    if(I==45);

            x1=-30;

            y1=-5;

            pause(1);

           p43=plot(x1,y1,'r*','linewidth',8);

            set(p42,'Visible','off');

            I=I+1;

    end

    if(I==46);

            x1=-30;

            y1=0;

            pause(1);

            p44=plot(x1,y1,'r*','linewidth',8);

            set(p43,'Visible','off');

            I=I+1;

    end

    if(I==47);

            x1=-30;

            y1=5;

            pause(1);

            p45=plot(x1,y1,'r*','linewidth',8);

            set(p44,'Visible','off');

            I=I+1;

    end

     if(I==48);

            x1=-30;

            y1=10;

            pause(1);

            p46=plot(x1,y1,'r*','linewidth',8);

            set(p45,'Visible','off');

            I=I+1;

     end

     if(I==49);

            x1=-30;

            y1=15;

            pause(1);

            p47=plot(x1,y1,'r*','linewidth',8);

            set(p46,'Visible','off');

            I=I+1;

     end

     if(I==50);

            x1=-30;

            y1=20;

            pause(1);

            p48=plot(x1,y1,'r*','linewidth',8);

            set(p47,'Visible','off');

            I=I+1;

     end   

     if(I==51);

            x1=-30;

            y1=25;

            pause(1);

            p49=plot(x1,y1,'r*','linewidth',8);

            set(p48,'Visible','off');

            I=I+1;

     end

     if(I==52);

            x1=-30;

            y1=30;

            pause(1);

            p50=plot(x1,y1,'r*','linewidth',8);

            set(p49,'Visible','off');

            I=I+1;

         end

Answer 1

[Michael Madelaire]

Hi, hope this is what you wanted. It is still rough, but you can always make it better :)

 I = 1;
x1= [-30 30];
y1=[30 30];
plot(x1,y1,'Linewidth',3);
hold on;
x2=[-30 30];
y2=[-30 -30];
plot(x2,y2,'Linewidth',3);
x3=[30 30];
y3=[-30 30];
plot(x3,y3,'Linewidth',3);
x4=[-30 -30];
y4=[-30 30];
plot(x4,y4,'Linewidth',3);
xlim([-40, 40]);
ylim([-40, 40]);
pause(1);
x = -30; y = 30;
p = plot(x, y, 'r*', 'LineWidth', 8);
for I = 1:48;

    if I < 13
        dx = 5; dy = 0;
    elseif I < 25
        dx = 0; dy = -5;
    elseif I < 37
        dx = -5; dy = 0;
    else
        dx = 0; dy = 5;
    end

    x = x + dx;
    y = y + dy;
    pause(1);
    p1 = plot(x, y, 'r*', 'LineWidth', 8);
    set(p, 'Visible', 'off');
    p = p1;
end

[VALARMATHY K]

Thank you very much.......