EXTERNAL

SUB scrsho (dum)

    DECLARE FUNCTION func         ! Supplied by the user

    LET iscr = 60
    LET jscr = 21
    DIM y(0), scr$(0,0)
    MAT redim y(iscr), scr$(iscr, jscr)

    LET blank$ = " "
    LET zero$ = "-"
    LET yy$ = "l"
    LET xx$ = "-"
    LET ff$ = "x"
    DO
       PRINT "Enter X1,X2 (= to stop)";
       INPUT x1, x2
       IF x1 = x2 then EXIT SUB
       FOR j = 1 to jscr
           LET scr$(1, j) = yy$
           LET scr$(iscr, j) = yy$
       NEXT j
       FOR i = 2 to iscr - 1
           LET scr$(i, 1) = xx$
           LET scr$(i, jscr) = xx$
           FOR j = 2 to jscr - 1
               LET scr$(i, j) = blank$
           NEXT j
       NEXT i
       LET dx = (x2 - x1) / (iscr - 1)
       LET x = x1
       LET ybig = 0
       LET ysml = ybig
       FOR i = 1 to iscr
           LET y(i) = func(x)
           IF y(i) < ysml then LET ysml = y(i)
           IF y(i) > ybig then LET ybig = y(i)
           LET x = x + dx
       NEXT i
       IF ybig = ysml then LET ybig = ysml + 1
       LET dyj = (jscr - 1) / (ybig - ysml)
       LET jz = 1 - ysml * dyj
       FOR i = 1 to iscr
           LET scr$(i, jz) = zero$
           LET j = 1 + (y(i) - ysml) * dyj
           LET scr$(i, j) = ff$
       NEXT i
       PRINT using "##.###^^^^": ybig;
       PRINT " ";
       FOR i = 1 to iscr
           PRINT scr$(i, jscr);
       NEXT i
       PRINT
       FOR j = jscr - 1 to 2 step -1
           PRINT "           ";
           FOR i = 1 to iscr
               PRINT scr$(i, j);
           NEXT i
           PRINT
       NEXT j
       PRINT using "##.###^^^^": ysml;
       PRINT " ";
       FOR i = 1 to iscr
           PRINT scr$(i, 1);
       NEXT i
       PRINT
       PRINT "           ";
       PRINT using "##.###^^^^": x1;
       PRINT repeat$(" ", 40);    ! Same as space$(40)
       PRINT using "##.###^^^^": x2
    LOOP

END SUB