Useful to plot points on Socratic Graph?
2 Answers
You may be able to add small circles to a graph using their equations.
Explanation:
Firstly, instead of requesting (say) a graph of
graph{(y-x^2)(x^2+y^2-0.04)((x-2)^2+(y-4)^2-0.04)((x+2)^2+(y-4)^2-0.04) = 0 [-5.165, 4.835, -0.46, 4.54]}
Graph a circle of small radius, centered at the point of interest.
Explanation:
To show the point
Graph
(Use some other radius if you prefer.)
graph{(x-2)^2+(y-3)^2 = 1/100 [-10, 10, -5, 5]}
For a single point, you can even fill in the circle by using an inequality:
graph{(x-2)^2+(y-3)^2 <= 1/100 [-10, 10, -5, 5]}
To plot two or more points, use circles in the form:
graph{((x-2)^2+(y-3)^2 - 1/100)((x-4)^2+(y+2)^2 - 1/100)=0 [-1.904, 15.874, -3.68, 5.21]}
The problem with this method is that it is very sensitive to zoom and centering. At some zooms/centers one or both circles will disappear.
Of course, you can use the same two equation idea to graph two curves:
Graph:
Using
graph{(y-x^2) (y-2x-4)= 0 [-11.25, 20.78, -3.48, 12.54]}