3 DIM X(70),Y(70)
5 PRINT "INPUT NUMBER OF KNOWN POINTS, N"  
10 INPUT N 
15 PRINT "INPUT KNOWN POINTS (1 POINT TO A LINE) AS FOLLOWS: 'X,Y'" 
20 FOR I=1 TO N 
25 INPUT X(I),Y(I)  
30 NEXT I 
35 PRINT "INPUT X-COORDINATE OF POINT TO BE INTERPOLATED. TO END" 
36 PRINT "KEY 99999"
47 PRINT 
60 PRINT "X"; 
65 INPUT Z 
67 IF Z=99999THEN 160
70 T=0  
75 FOR K=1 TO N 
80 S=1  
85 FOR I=1 TO N 
90 IF I=K THEN 100  
95 S=S*(Z-X(I))/(X(K)-X(I)) 
100 NEXT I  
110 T=T+S*Y(K)  
120 NEXT K  
130 PRINT "Y=";T 
140 PRINT 
150 GOTO 60 
160 END 

