How to sub sym to a number in a matrix

Hi all,

I have a code calculate the motion equation of 3DOF robotic arm.

In the code I use symbols such as

q = sym('q', [n 1], 'real');

Eventualy I have a 3x1 vector of the motion using alot of symbols on the way

for example, the output for row 1

val =

qdd2*(Izy2*cos(q1) + Izy3*cos(q1) - Izx2*sin(q1) - Izx3*sin(q1) + m3*(4*cos(q1)*sin(q2) +....

How can I subsitute those symbols, q1,q2,Izy,qdd2 and etc to a number?

I use diff() on the way to do diveration from the symbols (q1,q2,q3).,

so Im looking for a way to put the valuses of the symbols at the end, after calculating the motion equations.

I used sub(), didnt work..

thanks in advance.

Answer 1

[Walter Roberson]

subs(val, q(1:2), [VALUE1; VALUE2])

[Barak Bar-on]

where val is the equation,

and [VALUE1; VALUE2] are what i want q1,q2 to be?

[Walter Roberson]

yes

[Barak Bar-on]

thank, I had a problem with definde the sym on the vector.

thank you!

Answer 2

[John D'Errico]

syms x y z
M = [x-2,x+y,z^2]

M = 

subs(M,[x,z],[1 3])

ans = 

[Barak Bar-on]

thanks for the help!