!SQUARE ROOT ROUTINE

!KEN LOOSEMORE 17TH MARCH 1977

%CONTROL K'001001'
%EXTERNALROUTINE SQRT(%INTEGERNAME N1,N2)
   %INTEGER R2,INC,S1,S2

   %ROUTINE SQUARE(%INTEGERNAME S1,S2,%INTEGER R2)
      %INTEGER A,B,X,Y,Z,D
      A=R2//100
      B=R2-100*A
      X=A*A
      Y=A*B*2
      Z=B*B
      D=Y//100
      X=X+D
      Z=Z+(Y-100*D)*100
      D=Z//1000
      %IF X> 3276 %OR(X=3276 %AND D>7) %START
         S1=32767
         S2=32767
      %FINISH %ELSE %START
         S1=X*10+D
         S2=Z-1000*D
      %FINISH
   %END

   INC=X'2000'
   R2=0
   %WHILE INC>0 %CYCLE
      R2=R2+INC
      SQUARE(S1,S2,R2)
      %IF S1<=N1 %START
         %IF S1=N1 %AND S2>N2 %THEN R2=R2-INC
      %FINISH %ELSE R2=R2-INC
      INC=INC//2
   %REPEAT
   N1=R2//1000
   N2=R2-1000*N1
%END
%ENDOFFILE