How to convert symbolic matrix to numeric matrix ?

Let's say i have the following matrix a=[a1*b1, a2-a2, b2*b2; a1+a1, b2-b2, a2*a2] if you can see that the the first row second column contains the same value but subtracted so the value need to be 0 so how can i do this. i just will try to make analysis of 5DOF of robotic arm and i have a lot of values of Angles and have cos and sin so what will be the solution ?

thanks in advance.

Answer 1

[Walter Roberson]

simplify() of the matrix will cause it to take steps to try to resolve subtractions and so on. It is not always able to notice identities so it will not always work.

But this would not convert symbolic a1*b1 to numeric.

If your entries are symbolic numbers such as sin(3/84) then if there are no symbolic variables in the matrix then double() the matrix. If there are symbolic variables then vpa() the matrix, but that will not convert the symbolic variable to numeric.

[Mohammed kandeel]

I try to make the following in the m file

syms CO1 0 SO1 -CO1 L1 1 

T1=[CO1,0,SO1,0;SO1,0,-CO1,0;0,1,0,L1;0,0,0,1];

and i got this error

Error using syms (line 163) Not a valid variable name.

Error in Robotics_5DOF (line 1) syms CO1 0 SO1 -CO1 L1 1

[Walter Roberson]

 syms CO1 SO1 L1
 T1 = [CO1,0,SO1,0;SO1,0,-CO1,0;0,1,0,L1;0,0,0,1];

[Mohammed kandeel]

Walter thanks a looooooot