matlab function

when I use the function below:

syms x y z
f = [x*y*z; y; x + z];
v = [x, y, z];        
R = jacobian(f, v);

the result is :

R =
[ y*z, x*z, x*y]
[   0,   1,   0]
[   1,   0,   1];

However, I want to assign the real number to x y z, for example, x=1 y=2 z=3 , and get the real value of the R.How can I do this?

Thank you very much!

Answer 1

[Walter Roberson]

When you say "real value of R", do you mean as opposed to the imaginary part? If so, then use real (R) -- but don't expect the output to change much.

If when you say "real value of R", you are talking about the R that would result for particular values of x, y, and z, then you can subs() values in to R:

subs(R, {x, y}, {11.3, pi/42})

But if you are evaluating repeatedly you might want to use matlabFunction:

Rf = matlabFunction(R, x, y, z);

Then Rf would be a function handle that would accept 3 parameters and return the appropriate matrix.