cobweb diagrams Flashcards
(14 cards)
cobweb diagram
visual representation of DDS
stable
if diagram moves towards fixed point
unstable
if diagram moves away from fixed point
unstable spiral
moving away from f.p
y=ax+b where a<-1
stable staircase
moving towards f.p
y=ax+b where 0<=a<1
pos but less than 1
unstable staircase
moving away from f.p
y=ax+b where a>1
pos
square/periodic
y=-x/ y=-x+h
where line intersects with y=x line perpendicularly causing a square
every point f.p
y=b
every point on line will be a fixed point as the line goes back and forth
endless staircase
endless staircase with no fixed point.
where y=1x+b, line is parallel to y=x line
parallel lines never meet hence no f.p
stable spiral
moving towards f.p
y=ax+b
where -1<a<=0
cobweb graph
graph = map
xn+1 = 2xn + 3
graph: y=2x+3
x and y values
values on x-axis are input to go into xn
values on y axis: output/ result xn+1
fixed point
f.p is POI of 2 graphs
how to draw
- Draw a set of axes
- Draw y=x
- Draw y=ax+b
- NOTE - The f.p is @ POI of these lines
- Starting at x0, draw a vertical line that hits y=ax+b
Draw a horizontal line to y=x ( taking y output and turning it into input)
repeat
arrows!