DP Graph
DP Graph is a 3d plotting program we are using to plot direction fields.
To plot one or more functions:
graph3d((f1), (f2),...).
We are plotting direction fields via vectors, e.g.
graph3d( ( vector(a,(x - y)*a,0))
where the plot is of vectors with
components (a, a*y', 0):
this is a 3d vector but the z component is 0;
a is the length of the vector in the x direction;;
a can be changed by selecting the scrollbar menu and a, then using the right scrollbar.
graph3d( ( vector(a,(x - y)*a,0), x = 0, y = 0)) plots the x and y axes.
Code
a.minimum := -1; a, b, c, d are parameters you can use.
a.maximum := 1
b.minimum := -3 ;
b.maximum := 3
graph3d.view := top ; for 2-d
graph3d.perspective := false ;for 2-d
graph3d.resolution := 21 ; change this for denser or less dense vectors
graph3d.vectorcolor :=red ; or black, or green: See color menu bar.
graph3d.vectoralign := center ;(TAIL, center, or tip)
graph3d.vectorarrowhead := true
graph3d.background := white
graph3d.minimumx := -3; change min and max x , y to change range of graph
graph3d.maximumx := 3
graph3d.minimumy := -3
graph3d.maximumy := 3
graph3d.maximumz := 0 ; you have to have a little z depth because graph is 3d.
graph3d.maximumz := 1
graph3d( ( vector(a,(x - y)*a,0), x = 0, y = 0)); vector field of dy/dx= x-y
;graph3d( ( vector(a,(x - y)*a,0), y = x - 1 + b*e^(-x), x = 0, y = 0 ) ); with solution curve