Not enough input Arguments

Unfortunately, in line four it tells me that I am not passing enough input arguments. I don't quite understand how to fix the error? The code seems to be correct for me. I actually converted the code from python to matlab because in matlab I need the function.

Thanks for your help!

Code:

function e = angle_axis(T,Td)

e = [];
e(1:3) = Td(1:3,end)-T(1:3,end); % -> Mistake 
R = Td(1:3, 1:3) * T(1:3, 1:3).'; 
li = [R(2, 1) - R(1, 2), R(0, 2) - R(2, 0), R(1, 0) - R(0, 1)]; 

if any(li)
    % diagonal matrix case
    if trace(R) > 0 
        % (1,1,1) case 
        a = zeros(3,0); 
    else 
        a = pi/2*(diag(R)+1); 
    end 
else 
    ln = norm(li); 
    a = atan2(ln, trace(R)-1)*li/ln; 
end

e(3:1) = a; 


end

[Torsten]

In MATLAB, array indexing starts with 1, i.e. R(0,y) and R(x,0) errors.

[Christian Vogel]

Thanks for the note! I have corrected the mistake, but I still have the same problem....

[Torsten]

Then post your revised code together with the call to "angle_axis" and the error message you get.

And allocating zeros(3,0) also does not make much sense - you get an empty matrix.

[Christian Vogel]

Thanks for your help!

Answer 1

[KSSV]

The error is clear. You are trying to run the function by hitting the run button/ F5 key. You need to provide the inputs to the function and then call the function.

T = define your value ;
Td = define your value ; 
e = angle_axis(T,Td)  % now call the function 

[Christian Vogel]

Now I have following mistake, after I provide the inputs for the function (refer png)

Answer 2

[Christian Vogel]

That is the "translated" Matlab code:

function e = angle_axis(T,Td)

e = [];
e(1:3) = Td(1:3,end)-T(1:3,end); 
R = Td(1:3, 1:3) * T(1:3, 1:3).'; 
li = [R(3, 2) - R(2, 3), R(1, 3) - R(3, 1), R(2, 1) - R(1, 2)]; 

if any(li)
    % diagonal matrix case
    if trace(R) > 0 
        % (1,1,1) case 
        a = zeros(3,1); 
    else 
        a = pi/2*(diag(R)+1); 
    end 
else 
    ln = norm(li); 
    a = atan2(ln, trace(R)-1)*li/ln; 
end

e(3:1) = a; 


end

That is the python code:

def _angle_axis(T, Td):
    e = np.empty(6)
    e[:3] = Td[:3, -1] - T[:3, -1]
    R = Td[:3, :3] @ T[:3, :3].T
    li = np.array([R[2, 1] - R[1, 2], R[0, 2] - R[2, 0], R[1, 0] - R[0, 1]])

    if base.iszerovec(li):
        # diagonal matrix case
        if np.trace(R) > 0:
            # (1,1,1) case
            a = np.zeros((3,))
        else:
            a = np.pi / 2 * (np.diag(R) + 1)
    else:
        # non-diagonal matrix case
        ln = base.norm(li)
        a = math.atan2(ln, np.trace(R) - 1) * li / ln

    e[3:] = a

    return e
    

And when I run the Matlab code, I get following issue (please refer png data)

[Torsten]

Where is the call to "angle_axis" ?

You can not just run the function - it expects matrices T and Td. If you don't supply them, it has "not enough input arguments".

[Christian Vogel]

Sorry my fault! That was stupid of me.

I have following issue, when I run the function (refer png)

[Torsten]

In the last line of angle_axis, use

e(1:3) = a

instead of

e(3:1) = a

or whatever is senseful in this context (e(3:1) is empty).