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+//CHAPTER 3- THREE-PHASE A.C. CIRCUITS
+//Example 9
+
+clc;
+disp("CHAPTER 3");
+disp("EXAMPLE 9");
+
+//VARIABLE INITIALIZATION
+v_ab=400;                     //in Volts
+v_bc=400;                     //in Volts
+v_ac=400;                     //in Volts
+z_ab=100;                     //in Ohms
+z_bc=100;                     //in Ohms
+z_ac=100;                     //in Ohms
+
+//solution (a)
+
+//function to convert from polar to rectangular form
+function [x,y]=pol2rect(mag,angle);
+x=mag*cos(angle);
+y=mag*sin(angle);
+endfunction;
+
+I_AB=v_ab/z_ab;
+mag1=abs(real(I_AB));
+ang1=0;			       //I_AB is represented as mag1∠ang1
+I_BC=v_bc/z_bc;
+ang2=-210*(%pi/180);           //I_BC is represented as mag1∠ang2
+I_AC=v_ac/z_ac;
+ang3=210*(%pi/180);            //I_AB is represented as mag1∠ang3
+[x1,y1]=pol2rect(I_AB,ang1);
+[x2,y2]=pol2rect(I_BC,ang2);
+[x3,y3]=pol2rect(I_AC,ang3);
+//let us consider values X1, Y1, X2, Y2, X3 and Y3 for the ease of calculation (these are not mentioned in the book)
+X1=x1-x3;
+Y1=y1-y3;
+X2=x2-x1;
+Y2=y2-y1;
+X3=x3-x2;
+Y3=y3-y2; 
+I_A=X1+(%i*Y1);
+I_B=X2+(%i*Y2);
+I_C=X3+(%i*Y3);
+                       
+//function to convert from rectangular to polar form
+function [z,angle]=rect2pol(x,y);
+z=sqrt((x^2)+(y^2));              //z is impedance & the resultant of x and y
+if(x==0 & y>0) then angle=90;     //in case atan=∞ 
+elseif(x==0 & y<0) then angle=-90 //in case atan=-∞
+else
+angle=atan(y/x)*(180/%pi);        //to convert the angle from radians to degrees
+end;
+endfunction;
+
+[mag4,ang4]=rect2pol(X1,Y1);
+[mag5,ang5]=rect2pol(X2,Y2);
+[mag6,ang6]=rect2pol(X3,Y3);
+disp(sprintf("(a) The line current I_A is %f∠%f A",mag4,ang4));
+disp(sprintf("The line current I_B is %f∠%f A",mag5,(180+ang5)));
+disp(sprintf("The line current I_C is %f∠%f A",mag6,ang6));
+
+//solution (b)
+//since power is consumed only by 100Ω resistance in the arm AB
+r1=100;
+p1=(I_AB^2)*r1;
+p2=160000;
+r2=p2/p1;
+disp(sprintf("(b) The star connected balanced resistance is %d Ω",r2));
+
+//END 
+