var l, n, m, o, inc, xinc, yinc : int
var x, y, x2, y2, critical : real
var a, b, c, rootOne, rootTwo, scaleRootOne, scaleRootTwo, aS, bS, cS : real

var scale : real

locate (1, 18)
put "Quadratic Calculator and Plotter"
locate (3, 1)
put "       Usage:   Receives individual values for an equation in standard form:"
put "                axx+bx+c. Input as directed."
put ""
put "        Bugs:   What bugs? No, no. They're 'features'."
put ""
put "    Features:   Due to certain 'features' in Turing, this utility"
put "                cannot process complex numbers (imaginary roots)."
put ""
put "                The scaling is quite dumb. Currently, the only scale"
put "                available is 25ppu (pixels per unit)."
put ""
put "     Caveats:   No error traps! Avoid entering erroneous data."
put ""
put ""
put ""
put ""
put "      Author:   Omar Elkharadly. Questions? Comments? email: goatse@rogers.com"
put ""
put "     Enjoy."
put ""
put ""
put "                   push the 'any' key to continue."
procedure getKey
    var next : string (1)
    getch (next)
end getKey
getKey
cls
loop
    locate (1, 1)
    put "a: " ..
    get a
    locate (1, 1)
    put "       "
    locate (1, 1)
    put "b: " ..
    get b
    locate (1, 1)
    put "       "
    locate (1, 1)
    put "       "
    locate (1, 1)
    put "c: " ..
    get c

    locate (1, 1)
    put "       "
    %Calculate roots using the quadratic formula
    %form: ax^2 + bx + c
    rootOne := (-1 * b + sqrt ((b * b) - 4 * a * c)) / (2 * a)
    rootTwo := (-1 * b - sqrt ((b * b) - 4 * a * c)) / (2 * a)


    %Begin graph:




    %Set the scale for reasonable viewing (units:pixel)
    scale := .04

    %implement the scale!
    aS := a * scale
    bS := b
    cS := c / scale

    scaleRootOne := (-1 * bS + sqrt ((bS * bS) - 4 * aS * cS)) / (2 * aS)
    scaleRootTwo := (-1 * bS - sqrt ((bS * bS) - 4 * aS * cS)) / (2 * aS)
    %put scaleRootOne
    %put scaleRootTwo
    inc := -500
    xinc := 0
    yinc := 0
    for count : 1 .. 1000
	inc := -500 + count
	xinc := xinc + 25
	if xinc <= 640 then
	    drawline (xinc, 0, xinc, 480, 1)
	end if
	yinc := yinc + 25
	if yinc <= 480 then
	    drawline (0, yinc, 640, yinc, 1)
	end if
	x := inc
	y := aS * (x * x) + bS * x + cS
	x2 := x + 1
	if x = scaleRootOne or x = scaleRootTwo then
	    y2 := 0
	else
	    y2 := (y / (aS * x * x + bS * x + cS)) * aS * x2 * x2 + bS * x2 + cS
	end if
	%put x, ",",",y,",", x2, ",", y2
	l := round (x)
	m := round (y)
	n := round (x2)
	o := round (y2)


	drawline (l + 300, m + 150, n + 300, o + 150, 2)

    end for

    %Draw axes, more room is reserved for the first quadrant.
    drawline (0, 149, 640, 149, 4)
    drawline (0, 150, 640, 150, 4)
    drawline (0, 151, 640, 151, 4)
    drawline (299, 0, 299, 480, 4)
    drawline (300, 0, 300, 480, 4)
    drawline (301, 0, 301, 480, 4)

    %text output

    locate (19, 60)
    put a, "xx + ", b, "x + ", c
    locate (20, 60)
    put "(x,y)= ", "(", rootOne, ",", 0, ")"
    locate (21, 60)
    put "(x,y)= ", "(", rootTwo, ",", 0, ")"

    %Calculate max/min via symmetry
    critical := a * ((rootOne + rootTwo) / 2) * ((rootOne + rootTwo) / 2) + b * ((rootOne + rootTwo) / 2) + c

    if a < 0 then
	locate (22, 60)
	put "Max: (", ((rootOne + rootTwo) / 2), ",", critical, ")"
    else
	locate (22, 60)
	put "Min: (", ((rootOne + rootTwo) / 2), ",", critical, ")"

    end if

end loop