10 DEFINT A-Z: S=5: DIM M(S,S)
20 PRINT "Lower-triangular matrix:": GOSUB 200: GOSUB 100
30 PRINT "Upper-triangular matrix:": GOSUB 300: GOSUB 100
40 PRINT "Symmetric matrix:": GOSUB 400: GOSUB 100
50 END
100 REM *** Print the matrix M ***
110 FOR Y=1 TO S
120 FOR X=1 TO S
130 PRINT USING " ##";M(X,Y);
140 NEXT X
150 PRINT
160 NEXT Y
170 PRINT
180 RETURN
200 REM *** Generate the lower-triangular matrix ***
210 FOR X=1 TO S: FOR Y=1 TO S
220 ON -(X>Y)-2*(X=Y OR X=1) GOTO 240,250
230 M(X,Y)=M(X-1,Y-1)+M(X,Y-1): GOTO 260
240 M(X,Y)=0: GOTO 260
250 M(X,Y)=1: GOTO 260
260 NEXT Y,X
270 RETURN
300 REM *** Generate the upper-triangular matrix ***
310 FOR X=1 TO S: FOR Y=1 TO S
320 ON -(X<Y)-2*(X=Y OR Y=1) GOTO 340,350
330 M(X,Y)=M(X-1,Y-1)+M(X-1,Y): GOTO 360
340 M(X,Y)=0: GOTO 360
350 M(X,Y)=1: GOTO 360
360 NEXT Y,X
370 RETURN
400 REM *** Generate the symmetric matrix ***
410 FOR X=1 TO S: FOR Y=1 TO S
420 IF X=1 OR Y=1 THEN M(X,Y)=1 ELSE M(X,Y)=M(X-1,Y)+M(X,Y-1)
430 NEXT Y,X
440 RETURN