About getting answers with "SYM" function

Hi guys,

Now I am try to getting start with Matlab.

I get a equation

Px=sym('(L1+L2*cos(A2)+L3*cos(A2+A3))*cos(A1)')

A1 A2 A3 L1 L2 L3 are some variables

How can I put the value to those variables and finally get the value of Px?

Thanks a lot!!

[Bruno Pop-Stefanov]

What are you trying to do with sym? If you just want to evaluate this formula given your variables then:

A1 = 1;
A2 = 2;
A3 = 3;
L1 = 11;
L2 = 22;
L3 = 33;
Px = ( L1 + L2*cos(A2) + L3*cos(A2+A3) )*cos(A1)

will give you the answer.

[Chan]

Thanks for your help! it helpful.

But I still got other problem.

Now I have 3 equation.

Px=(L1+L2*cos(A2)+L3*cos(A2+A3))*cos(A1)

Py=(L1+L2*cos(A2)+L3*cos(A2+A3))*sin(A1)

Pz=(L2*sin(A2)+L3*sin(A2+A3))

Any methods that matlab can help me to transfer the equations like this:

A1=????????????

A2=????????????

A3=????????????

Because I need to know each value of A1 A2 A3 by given Px,Py,Pz,L1,L2,L3.

Thanks!!!

Answer 1

[Walter Roberson]

   solve(Px==(L1+L2*cos(A2)+L3*cos(A2+A3))*cos(A1), Py==(L1+L2*cos(A2)+L3*cos(A2+A3))*sin(A1), Pz==(L2*sin(A2)+L3*sin(A2+A3)), A1, A2, A3)