SCREEN 12
VIEW (90, 36)-(638, 348), 8, 12      'Grey box with red border
WINDOW (0, 0)-(10, 40)               'Set scale
LINE (0, 0)-(10, 0), 9               'Draw axis

PRINT "The vertical scale is 0 to + 40, horizontal is 0 to 10.  ";
x0 = 0: u = 10
PRINT "The input ="; u
PRINT "Test the effect of various steplengths from .001 to 5, zero to end."
PRINT
k = .5
DO
   INPUT "Step "; dt: IF dt <= 0 THEN END
   x = x0
   t = 0
   PSET (0, x0)                      'Move pen to starting point
   DO
      x = x + (-k * x + u) * dt      'This is the simulation
      t = t + dt
      LINE -(t, x)                   'This displays the result as lines
   LOOP UNTIL t > 10
LOOP