Finding Singularity of Jacobian Matrix (MATLAB)

I have a Jacobian matrix containing symbolic variables. Can I find the values of those variables which make the Jacobian matrix singular (loses its rank)?

Note: Jacobian matrix dimension is 3*4

[Torsten]

How do you define "Singularity" of a non-square matrix A ?

If A is (mxn), do you mean that rank(A) < min(m,n) ?

[Prasanna Venkatesh]

@Torsten

Yes.

[Torsten]

Apply Gauss-Jordan elimination to the matrix and see for which values of the symbolic variables the elements (1,1),(2,2) and (3,3) of the resulting matrix can become zero.

Maybe MATLAB's "rref" can help although I don't know whether it can be applied to non-square matrices.

[Prasanna Venkatesh]

I tried this. But rref(A) is returning 3x4 matrix with constants in the subscripts ([1,1], [2,2], [3,3]). They are not funciton of those variables.

[Torsten]

Please show your code.

[Prasanna Venkatesh]

>> rref(jac)
 
ans =
 
[ 1, 0,                                      -sin(t3)/(sin(t2)*cos(t3)^2 + sin(t2)*cos(t3) + sin(t2)*sin(t3)^2 + cos(t2)*sin(t3)), 0]
[ 0, 1, (sin(t3) + cos(t2)*sin(t3) + cos(t3)*sin(t2))/(sin(t2)*cos(t3)^2 + sin(t2)*cos(t3) + sin(t2)*sin(t3)^2 + cos(t2)*sin(t3)), 0]
[ 0, 0,                                                                                                                         0, 1]

[Bruno Luong]

That means your matrix is always of rank 3.