C DEMOF3.FOR     VERSION PROVIDED
C THIS PROGRAM PRODUCES A PLOT ON THE TERMINAL
C OF AN EXTERNAL FUNCTION, FUN(X,Y)
C THE LIMITS OF THE PLOT ARE DETERMINED BY THE DATA STATEMENTS
C "STAB" IS FILLED WITH A TABLE OF HEIGHT FLAGS
C "STRING" IS USED TO BUILD A LINE OF GRAPH FOR PRINTING
C
        LOGICAL*1 STRING(13,3),STAB(100)
        DATA XMIN,XMAX,MAXX/ -5.0, 5.0, 45/
        DATA YMIN,YMAX,MAXY/ -5.0 ,5.0, 72/
        DATA FMIN,FMAX/0.0,1.0/
C
        SCAL(ZMIN,ZMAX,MAXZ,K)=ZMIN+FLOAT(K-1)*(ZMAX-ZMIN)/FLOAT(MAXZ-1)
C
        CALL SCOPY('- 1 2 3 4 5 6 7 8 9 +',STAB)
        MAXF=LEN(STAB)
        DO 20 IX=1,MAXX
          X=SCAL(XMIN,XMAX,MAXX,IX)
          CALL REPEAT('*',STRING,MAXY)
          IF(IX.EQ.1 .OR. IX.EQ.MAXX) GOTO 20
            DO 10 IY=2,MAXY-1
              Y=SCAL(YMIN,YMAX,MAXY,IY)
              IFUN = 2 + INT(FLOAT(MAXF-3)*(FUN(X,Y)-FMIN)/(FMAX-FMIN))
10            STRING(IY)=STAB(MIN0(MAXF,MAX0(1,IFUN)))
30        WRITE (7, 1001) (STRING(I),I=1,MAXY)
1001      FORMAT (' ', 72A1)
        CALL EXIT
        END
C
        FUNCTION FUN(X,Y)
        R=SQRT(X**2+Y**2)
        FUN=X*Y*R*EXP(-R))**2
        RETURN
        END