OpenEuphoria

Re: Converting qbasic to Euphoria?

• Posted by Matt Lewis <matthewwalkerlewis at yahoo.com> Jul 28, 2004
• 588 views

Ed Davis wrote:
> 
> Can the following qbasic code be easily converted to Euphoria?
> Note that I am not looking for an exact translation. My goal is
> to be able to use Euphoria to graph some simple algebraic
> equations.  Using DOS (as opposed to Linux or Windows) is ok too.
> 
> Thanks for any help!
> 
> DIM a, b, c, x AS DOUBLE
> SCREEN (12)
> WINDOW (-8, 6)-(8, -6)
> LINE (-8, 0)-(8, 0)   'X axis
> LINE (0, 6)-(0, -6)   'Y axis
> FOR x = -8 TO 8 STEP .025
>     a = x ^ 2
>     b = SIN(x)
>     c = COS(x)
>     PSET (x, a)
>     PSET (x, b)
>     PSET (x, c)
> NEXT x

You could do this fairly easily using matheval.  You'll need to update
the grapheval.e file:

The line towards the top (add CONSTANT, VAR):

integer INVALID, DATA, GRAPH, CGRAPH, RANGE, CONSTANT, VAR

And graph_init() should look like:

procedure graph_init()
    INVALID = resolve_math_ref( "INVALID" )
    DATA = resolve_math_ref( "DATA" )
    CONSTANT = resolve_math_ref( "CONSTANT" )
    VAR = resolve_math_ref( "VAR") 

    GRAPH = reg_math_func( "GRAPH", routine_id("Graph") )
    CGRAPH = reg_math_func( "CGRAPH", routine_id("CGraph") )
    RANGE = reg_math_func( "RANGE", routine_id("Range") )

end procedure

Then try the following (uses Win32Lib):

without warning
include win32lib.ew
include matheval.e
include grapheval.e

constant 
win	= create( Window, "Graph", 0, Default, Default, 500, 420, 0 )

sequence graph, func, colors
integer GRAPH

procedure win_paint( integer self, atom event, sequence params )
	setPenColor( win, BrightWhite )
	drawPolygon( win, 1, { 10, 10, 490, 10, 490, 390, 10, 390 } )
	for i = 1 to 3 do
		drawLines( win, colors[i] & graph[i] )
	end for
	setPenColor( win, Black )
	drawPolygon( win, 0, { 10, 10, 490, 10, 490, 390, 10, 390 } )
	drawLine( win, 250, 10, 250, 390)
	drawLine( win, 10, 200, 490, 200)
end procedure
setHandler( win, w32HPaint, routine_id("win_paint"))

procedure setup()
	sequence g
	matheval_init()
	GRAPH = resolve_math_ref( "GRAPH" )
	func = {
			Parse( "x^2" ),
			Parse( "sin(x)" ),
			Parse( "cos(x)" )
			}
	
	colors = {Blue, Green, Red}
	
	graph = repeat( 0, 3 )
	SetScreen( {480, 380})
	SetOrigin({10,10})

	for i = 1 to 3 do
		g = Evaluate({ GRAPH, { func[i], "X"}, {-8, 8, 0.1, -6, 6} })
		g = floor(g[2])
		g[2] = g[1] & g[2]
		graph[i] = g[2..length(g)]
	end for
end procedure
setup()

WinMain( win, Normal )

Matt Lewis