how to create equation x y z using matlab

hi all,

anyone can help me how to create equation using data x,y,z??

Please help me

let say below is my data

x = [5.252907987, 1.945397314, 1.016, 0.243];

y = [287.4171875, 137.4367188, 80.08359375, 37.798];

z = [25.16096572, 23.53767761, 22.72603356, 9.740];

[Ameer Hamza]

How do you want to create equation? Give an example of your equations with vectors x, y, and z.

Answer 1

[Star Strider]

If you simply want to plot them:

x = [5.252907987, 1.945397314, 1.016, 0.243];
y = [287.4171875, 137.4367188, 80.08359375, 37.798];
z = [25.16096572, 23.53767761, 22.72603356, 9.740];

figure
plot3(x, y, z)
grid on
view(35,20)

[mohd akmal masud]

so do you know how to create the equation from that graf?

[Star Strider]

There are any number of possible equations that could fit those data. The correct one would be a function that is the mathematical model of the process that created them. You would have to decide on the most appropriate one.

A linear fit:

x = [5.252907987, 1.945397314, 1.016, 0.243];
y = [287.4171875, 137.4367188, 80.08359375, 37.798];
z = [25.16096572, 23.53767761, 22.72603356, 9.740];

DM = [x(:) y(:) ones(size(x(:)))];                      % Design Matrix
B = DM \ z(:);                                          % Estimate Parameters
ze = DM * B;                                            % Fit Data

figure
plot3(x, y, z)
hold on
plot3(x(:), y(:), ze, '-r'), 
hold off
grid on
view(35,20)

Experiment with different linear and nonlinear models to get different results.

[mohd akmal masud]

sir, my experiments is nonlinear models. so how? please help me sir what is the equation

[Star Strider]

Please post the model, preferably both as LaTeX and as you have coded it.

Note that using the data you posted, it must not have more thann 3 parameters.

Answer 2

[mohd akmal masud]

Because my theori is

When x is increase, y should increase. But I have to consider z. Because some time is when x is increase, y not increase because of z.

Do you have any idea . Or how to plot that Graf x y z