How do I plot 3d graph ?

So I have this 26x4 matrix and I need to plot a 3d matrix for the first 3 coloumns. The following is my code :

impval = xlsread('Values_sweep.xlsx');
vol_data = impval(1:end,1); %data.VolumeSystem
density_data = impval(1:end,2); %data.PowerDensity
power_data = impval(1:end,3);%data.Power
distance_data = impval(1:end,4);%data.distance
x = vol_data;
y = power_data;
z = density_data;
[X,Y] = meshgrid(x,y);

How do I then plot in 3d. I want to plot for the vol_data, density_data and power_data but I'm getting error 'Z must be a matrix , not a scalar or vector'

Answer 1

[Jonas]

what about plot3(x,y,z) without the meshgrid?

[Urvashi Agrawal]

I tried it , but I'm more interested in having a proper surface /mesh grid plot .

Answer 2

[Star Strider]

Interpolate!

N = 50;
xv = linspace(min(x), max(x), N);
yv = linspace(min(y),m max(y), N);
[Xm,Ym] = ndgrid(xv, yv);
Zm = griddata(x, y, z, Xm, Ym);

figure
surfc(Xm, Ym, Zm)
grid on

See the griddata documentation for details.

This is prototype code. Note than ‘N’ can be any value that works, and does not have to be the same for both ‘xv’ and ‘yv’.

.

[Urvashi Agrawal]

Not exactly what I was hoping..

[Star Strider]

The data are the data.

Note — The x-axis is the scale of the y-axis and z-axis. If you want to plot it as a (relatively narrow) surface that may be more representative, use:

axis('equal')

after the surf call.

If you plot it with plot3 or scatter3, the plot should look similar to what you got with my code. Another option is stem3 if you want to see precisely where on the (x,y) plane the points originated.

.