Help writing a function

Can someone please help on how to write the following function please.

I have 3 3x3 Rotation Matrices.

2 of which are Identity Matrices.

R1 = eye(3,3)
R2 = eye(3,3)

% R3 Rotation Value Kappa Pre-Cal 
R3(3,3) = zeros
R3(1,1) = cos(xHat_BM(3,1))
R3(1,2) = sin(xHat_BM(3,1))
R3(2,1) = -sin(xHat_BM(3,1))
R3(2,2) = cos(xHat_BM(3,1))
R3(3,3) = 1

xHat_BM will be updated for each iteration (separate section of code)

How do I create a function so that said function grabs the xHat_BM value from the script, uses it for the rotation angle calculations (R3 elements in the function), then outputs the updated R3 matrix (M_BM)back into the script for the next iteration?

Thanks in advance.

Answer 1

[Walter Roberson]

function R3 = update_R3(xHat_BM)

    % R3 Rotation Value Kappa Pre-Cal 
    R3 = zeros(3,3);
    R3(1,1) = cos(xHat_BM(3,1));
    R3(1,2) = sin(xHat_BM(3,1));
    R3(2,1) = -sin(xHat_BM(3,1));
    R3(2,2) = cos(xHat_BM(3,1));
    R3(3,3) = 1;

To use: have your script call

M_BM = update_R3(xHat_BM);