Matrix Multiplication with Trigonometric Functions

a = theta1

b = theta2

A = [cos(a+pi) -sin(a+pi)cos(pi/2) sin(a+pi)sin(pi/2) -0.033cos(a+pi);
    sin(a+pi) cos(a+pi)cos(pi/2) -cos(a+pi)sin(pi/2) -0.033sin(a+pi);
    0 sin(pi/2) cos(pi/2) 0.145;
    0 0 0 1]

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.

Error in connector.internal.fevalMatlab

Error in connector.internal.fevalJSON

B = [cos(b+(pi/2)) -sin(b+(pi/2))cos(0) sin(b+(pi/2))sin(0) 0.155cos(b+(pi/2));
    sin(b+(pi/2)) cos(b+(pi/2))cos(0) -cos(b+(pi/2))sin(0) 0.155sin(b+(pi/2));
    0 sin(0) cos(0) 0;
    0 0 0 1]

Answer = A*B;

Answer 1

[Rik]

The solution is in the error message: in Matlab you need to explicitly use the * operator. In mathematical notation you can generally leave those out, but here you need them.

[N Soomro]

a = theta1

Unrecognized function or variable 'theta1'.

b = theta2


A = [cos(a+pi) (-sin(a+pi))*cos(pi/2) (sin(a+pi))*sin(pi/2) -0.033*cos(a+pi);
    sin(a+pi) (cos(a+pi))*cos(pi/2) (-cos(a+pi))*sin(pi/2) -0.033*sin(a+pi);
    0 sin(pi/2) cos(pi/2) 0.145;
    0 0 0 1];

B = [cos(b+(pi/2)) -sin(b+(pi/2))*(cos(0)) sin(b+(pi/2))*(sin(0)) 0.155*cos(b+(pi/2));
    sin(b+(pi/2)) cos(b+(pi/2))*(cos(0)) -cos(b+(pi/2))*(sin(0)) 0.155*sin(b+(pi/2));
    0 sin(0) cos(0) 0;
    0 0 0 1];

Answer = A*B;

[Rik]

If you define theta1 and theta2 as variables, your code runs:

theta1=pi*2/3;theta2=2;

a = theta1;

b = theta2;


A = [cos(a+pi) (-sin(a+pi))*cos(pi/2) (sin(a+pi))*sin(pi/2) -0.033*cos(a+pi);
    sin(a+pi) (cos(a+pi))*cos(pi/2) (-cos(a+pi))*sin(pi/2) -0.033*sin(a+pi);
    0 sin(pi/2) cos(pi/2) 0.145;
    0 0 0 1];

B = [cos(b+(pi/2)) -sin(b+(pi/2))*(cos(0)) sin(b+(pi/2))*(sin(0)) 0.155*cos(b+(pi/2));
    sin(b+(pi/2)) cos(b+(pi/2))*(cos(0)) -cos(b+(pi/2))*(sin(0)) 0.155*sin(b+(pi/2));
    0 sin(0) cos(0) 0;
    0 0 0 1];

Answer = A*B

Answer = 4×4

-0.4546 0.2081 -0.8660 -0.0870 0.7875 -0.3604 -0.5000 0.1506 -0.4161 -0.9093 0.0000 0.0805 0 0 0 1.0000

[N Soomro]

This is actually what I am trying to implement in MATLAB

[Walter Roberson]

syms theta_1 theta_2
pi = sym(pi);

a = theta_1;

b = theta_2;


A = [cos(a+pi) (-sin(a+pi))*cos(pi/2) (sin(a+pi))*sin(pi/2) -0.033*cos(a+pi);
    sin(a+pi) (cos(a+pi))*cos(pi/2) (-cos(a+pi))*sin(pi/2) -0.033*sin(a+pi);
    0 sin(pi/2) cos(pi/2) 0.145;
    0 0 0 1];

B = [cos(b+(pi/2)) -sin(b+(pi/2))*(cos(0)) sin(b+(pi/2))*(sin(0)) 0.155*cos(b+(pi/2));
    sin(b+(pi/2)) cos(b+(pi/2))*(cos(0)) -cos(b+(pi/2))*(sin(0)) 0.155*sin(b+(pi/2));
    0 sin(0) cos(0) 0;
    0 0 0 1];

Answer = A*B

Answer = 

simplify(Answer)

ans = 

[N Soomro]

This is what I was looking for. Thanks a million Mr. Walter Roberson.