Function for symbolic expression with only some variable among all variables

Hi,

I have this symbolic expression:

J =

[ - a2*sin(t1 + t2) - a1*sin(t1), -a2*sin(t1 + t2)]
[   a2*cos(t1 + t2) + a1*cos(t1),  a2*cos(t1 + t2)]
[                              0,                0]
[                              0,                0]
[                              0,                0]
[                              1,                1]

where symvar are:

[ a1, a2, t1, t2]

I saw that I can convert this symbolic expression by matlabFunction command but variables/function-input must be [ a1, a2, t1, t2].

Because I want to put resultant function into a Interpreted MATLAB Function block, how can I assign only t2 as "input" and the others like mask-parameters ? There is a way to convert J to a matlab function with only t2 as input?

Answer 1

[Shashank Prasanna]

You can use anonymous function to do that. However make sure that the other 3 variables a1 a2 t2 are also defined in the function other wise it will error out.

>> Jfun = matlabFunction(J)

Jfun = 

    @(a1,a2,t1,t2)reshape([-a2.*sin(t1+t2)-a1.*sin(t1),a2.*cos(t1+t2)+a1.*cos(t1),0.0,0.0,0.0,1.0,-a2.*sin(t1+t2),a2.*cos(t1+t2),0.0,0.0,0.0,1.0],[6,2])

>> Jfunt2 = @(t2)Jfun

Jfunt2 = 

      @(t2)Jfun

This was you can call Jfunt2 with only t2 as input arguments, but make sure the other 3 variables are defined someone above.

[Walter Roberson]

You would need

Jfunt2 = @(t2)Jfun(a1, a2, t1, t2)

where a1, a2, t1 were defined in scope when the anonymous function was defined.

[Walter Roberson]

I am concerned here about whether Simulink MATLAB functions are permitted to use anonymous functions (or function handles). I do not recall that as being one of the permitted datatypes in such functions. I might be getting confused on terminology, though, about which Simulink MATLAB functions are executed in MATLAB as a whole and which ones have to conform to the embedded function requirements.