Graphing a Function

 

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Draw a graph with lingo

-- some parameters to govern the way the graph displays   -- set these before actually running drawGraph   global xMin, xMax         -- range of values of x for which to compute y   global yMin, yMax         -- range of values for y to display   global xPrecision         -- number of steps to draw   -- for the sake of argument, we"ll put a sprite in channel 1 to specify   -- the bounds within which the graph is to be drawn, and put the drawing   -- implement (a sprite containing a dot with trails on) in channel 2   on drawGraph     -- calculate scale factors     set xRange = XMax - XMin     set graphWidth = the right of sprite 1 - the left of sprite 1     set xScale = float(graphWidth)/xRange     set yRange = YMax - YMin     set graphHeight = the bottom of sprite 1 - the top of sprite 1     set yScale = float(graphHeight)/yRange     set xBase = the left of sprite 1     set yBase = the bottom of sprite 1     -- calculate the difference between consecutive x values used     set xInterval = float(xRange)/xPrecision     repeat with i = 0 to xPrecision       -- calculate x and y       set x = xMin + xInterval * i       set y = yourFunction(x)       -- scale and offset them to stage coordinates       set h = xBase + integer( i * xInterval * xScale )       set v = yBase - integer( (y - yMin) * yScale )       -- draw the point if it"s within the constraining sprite       if v <= yBase and v >= the top of sprite 1 then         set the locH of sprite 2 = h         set the locV of sprite 2 = v         updateStage       end if      end repeat   end drawGraph