'===========================================================================
' Subject: GRAPHING PROGRAM                   Date: 12-27-95 (00:13)       
'  Author: Aaron Scott Zabudsky               Code: QB, QBasic, PDS        
'  Origin: zabudsk@ecf.toronto.edu          Packet: ALGOR.ABC
'===========================================================================
DECLARE SUB pprint (x!, y!, A$)
SCREEN 12
PALETTE 0, 63 + 256 * 63 + 65536 * 63
PALETTE 15, 0
sx = 640
sy = 480
axisc = 12
gridc = 9
autounits = 1
xunitovr = .2
yunitovr = .2
xmin = -5
xmax = 5
ymin = -5
ymax = 5

IF xmin <= 0 AND xmax >= 0 THEN
   LINE (((0 - xmin) / (xmax - xmin)) * sx - 1, 0)-(((0 - xmin) / (xmax - xmin)) * sx + 1, sy), axisc, BF
END IF
IF ymin <= 0 AND ymax >= 0 THEN
   LINE (0, sy - ((0 - ymin) / (ymax - ymin)) * sy - 1)-(sx, sy - ((0 - ymin) / (ymax - ymin)) * sy + 1), axisc, BF
END IF

IF autounits = 1 THEN
   xunitovr = (xmax - xmin) / 10
   yunitovr = (ymax - ymin) / 10
   rx = 0
   ry = 0
   IF xunitovr < 1 THEN
      WHILE xunitovr < 1
         xunitovr = xunitovr * 10
         rx = rx - 1
      WEND
   END IF
   IF xunitovr >= 10 THEN
      WHILE xunitovr >= 10
         xunitovr = xunitovr / 10
         rx = rx + 1
      WEND
   END IF
   IF xunitovr < 1.5 THEN xunitovr = 1
   IF xunitovr >= 1.5 AND xunitovr < 3.5 THEN xunitovr = 2
   IF xunitovr >= 3.5 AND xunitovr < 7.5 THEN xunitovr = 5
   IF xunitovr >= 7.5 THEN xunitovr = 10
   xunitovr = xunitovr * 10 ^ rx
   IF yunitovr < 1 THEN
      WHILE yunitovr < 1
         yunitovr = yunitovr * 10
         ry = ry - 1
      WEND
   END IF
   IF yunitovr >= 10 THEN
      WHILE yunitovr >= 10
         yunitovr = yunitovr / 10
         ry = ry + 1
      WEND
   END IF

   IF yunitovr < 1.5 THEN yunitovr = 1
   IF yunitovr >= 1.5 AND yunitovr < 3.5 THEN yunitovr = 2
   IF yunitovr >= 3.5 AND yunitovr < 7.5 THEN yunitovr = 5
   IF yunitovr >= 7.5 THEN yunitovr = 10
   yunitovr = yunitovr * 10 ^ ry
END IF



FOR x = (INT(xmin / xunitovr) - 1) * xunitovr TO (INT(xmax / xunitovr) + 1) * xunitovr STEP xunitovr
   LINE ((x - xmin) / (xmax - xmin) * sx, 0)-((x - xmin) / (xmax - xmin) * sx, sy), gridc
NEXT x
FOR y = (INT(ymin / yunitovr) - 1) * yunitovr TO (INT(ymax / yunitovr) + 1) * yunitovr STEP yunitovr
   LINE (0, sy - ((y - ymin) / (ymax - ymin)) * sy)-(sx, sy - ((y - ymin) / (ymax - ymin)) * sy), gridc
NEXT y
x = 50
y = 50
c = 0
WHILE c < 3
x = x + 1
IF c = 1 THEN xb = x + 1
IF POINT(x, y) = axisc THEN c = 0
IF POINT(x, y) = gridc THEN c = c + 1
WEND
c = 0
x = xb
WHILE c < 3
y = y + 1
IF c = 1 THEN yb = y + 1
IF POINT(x, y) = axisc THEN c = 0
IF POINT(x, y) = gridc THEN c = c + 1
WEND
xb = xb + 16
yb = yb + 32
fx = INT(xb / 8)
fy = INT(yb / 16)
xb = fx * 8
yb = fy * 16
IF xmin <= 0 AND xmax - xunitovr >= 0 THEN
   px = ((0 - xmin) / (xmax - xmin)) * sx
   FOR y = 20 TO sy
      IF POINT(px + 2, y) = gridc THEN pprint px, y - 19, STR$(INT((((sy - y) * (ymax - ymin)) / sy + ymin) / yunitovr + yunitovr * .1) * yunitovr)
   NEXT y
ELSE
   FOR y = 20 TO sy
      IF POINT(2, y) = gridc THEN pprint 0, y - 19, STR$(INT((((sy - y) * (ymax - ymin)) / sy + ymin) / yunitovr + yunitovr * .1) * yunitovr)
   NEXT y
END IF

IF ymin < 0 AND ymax - yunitovr >= 0 THEN
   py = sy - ((0 - ymin) / (ymax - ymin)) * sy
   FOR x = 0 TO sx
      IF POINT(x, py + 2) = gridc THEN pprint x, py + 2, STR$(INT((((x) * (xmax - xmin)) / sx + xmin) / xunitovr + xunitovr * .1) * xunitovr)
   NEXT x
ELSE
   FOR x = 0 TO sx
      IF POINT(x, 2) = gridc THEN pprint x, sy - 18, STR$(INT((((x) * (xmax - xmin)) / sx + xmin) / xunitovr + xunitovr * .1) * xunitovr)
   NEXT x
END IF

pprint 610, 232, "x"
pprint 308, 10, "y"
pprint 200, 140, "y = x  + 2"
pprint 240, 130, "2"

rep:
undefval = xmin - 1
xb = xmin
IF xmin <> undefval THEN
   yb = xmin ^ 2 + 2
ELSE skip = 1
END IF
gradx = (xmax - xmin) / sx
FOR x = (xmin + gradx) TO xmax STEP gradx
IF x <> undefval THEN
   y = x ^ 2 + 2
ELSE skip = 1
END IF

IF y <= ymax AND y >= ymin AND skip = 0 THEN LINE (((xb - xmin) / (xmax - xmin)) * sx, sy - ((yb - ymin) / (ymax - ymin)) * sy)-(((x - xmin) / (xmax - xmin)) * sx, sy - ((y - ymin) / (ymax - ymin)) * sy), 15
yb = y
xb = x
IF skip = 1 THEN skip = 0
NEXT x


WHILE INKEY$ = ""
WEND

GOTO rep

SUB pprint (x, y, A$)
SHARED fy, fx, xb, yb, sx, sy
DIM B(16)  AS LONG
A$ = LTRIM$(RTRIM$(A$))
FOR d = 1 TO LEN(A$)
LOCATE fy, fx
PRINT MID$(A$, d, 1)
REM LINE (xb - 10, yb - 18)-(xb - 1, yb - 1), 3, B
GET (xb - 9, yb - 17)-(xb - 2, yb - 2), B
IF (x + d * 8) <= sx - 8 AND y <= sy - 16 THEN PUT (x + d * 8, y), B, PSET
NEXT d
LOCATE fy, fx
PRINT " "
END SUB