how to plote 3 variable on 2D plot

Hi guys

I have two matrices; one for velocity and the other for depth. these two matrices will generate a curve at particular position where the test was made. Similarly, at every x(i) position we have different curve from different data. I am trying to plot 2D (velocity VS depth) at all position but on the same plot. The problem is I want the x axis to present the velocity and axial distance x(i) and y present the depth. example x=[ 0,1,2,3,4] and at every x value we have D matrix and V matrix. The plot should draw this matrices at every element of x.

Thanks in advance Aziz

Answer 1

[Ahmed A. Selman]

But the single x-axis can't hold more than one variable, unless:

• The two (or more) variables have the same units, as the radius of a sphere (R) and the outward distance (D) from the surface of that sphere, or
• The two (or more) variables are coupled by a linear equation, as the radius of a sphere (R) and the circumference of that sphere (C=2*pi*R). In this case the scale units might be (arbitrary).

None of these cases apply to your question, since you have velocity (units of length/time) and depth, or axial distance (units of length).

There is a way around it, that is to use two y-axes on a single x-axis (x and V, x and D). For such case use

plotyy(x1, D, x2, V)% two x-axes, two y-axes. Or
plotyy(x, D, x, V)% one x-axes, two y-axes.

and always note that (x, D and V) must have the same sizes.