The first thing that we must do is to select an equation that we want to investigate. Let us start with the exponential function. For Y1, store "Y1=exp^(X). Turn the plotting option off of Y1. Input Y2 as the anti-derivative. Clear all the other Y function variables. Remember that this is the derivative of the function that we are trying to find.

Let d=dx and n=number of time steps.

:euler()

:Prgm"euler".

:setMode("Exa/Approx","AUTO")

:DelVar l1, l2, l3

:{0}=>l1

:l1=>l2

:Input "xo", a

:Input "yo", b

:Input "dx", d

:Input "number of steps",n

:a=>l1[1]

:b=>l2[1]

:For i, 1, n

:a+d*i=>l1[i+1]

:l2[i]+d*y1(l1[i])=>l2[i+1]

:EndFor

:PlotsOff

:FnOff

:FnOn 2

:NewPlot 1, 1, l1, l2, , , , 5

:ZoomData

:0=>ymin

:PxlText "y=", 1, 85

:PxlText string(y2(x)), 1, 97

:Pause

:ClrDraw

:abs((y2(l1)-l2)/(y2(l1)))=>l3

:FnOff

:NewPlot 1, 1, l1, l3, , , , 5

:ZoomData

:0=>ymin

:PxlText "Relative Error", 1, 80

:PxlText "Max Error=", 10, 25

:PxlText string(round(max(l3),5)), 10, 85

:EndPrgm