DIM A(20, 21), X(20)
PRINT "N"; \ INPUT N
GOSUB 100
GOSUB 200
IF S = 0 THEN PRINT "DET=0" \ GO TO 20
FOR I = 1 T ON \ PRINT "X"I"="X(I) \ NEXT I
GO TO 20
FOR I = 1 TO N
FOR J = 1 TO N+1 \ PRINT "A"I;J; \ INPUT A(I,J) \ NEXT J
NEXT I
RETURN
N1=N+1
FOR K=1 TO N\ K1=K+1 \ S=A(K,K) \ J=K
FOR I=K1 TO N \ R=A(I,K)
IF ABS(R) > ABS(S) THEN S=R \ J=I
NEXT I
IF S = 0 THEN RETURN
IF J=K THEN 280
FOR I=K TO N1 \ R=A(K,I) \ A(K,I)=A(J,I) \ A(J,I)=R \ NEXT I
FOR J=K1 TO N1 \ A(K,J)=A(K,J)/S \ NEXT J
FOR I=K1 TO N \ R=A(I,K)
FOR J=K1 TO N1 \ A(I,J)=A(I,J)-A(K,J)*R \ NEXT J
NEXT I
NEXT K
FOR I=N TO STEP -1 \ S=A(I,N1)
FOR J=I+1 TO N \ S=S-A(I,J)*X(J) \ NEXT J
X(I)=S \ NEXT I
RETURN