Question about vector function integration

[Corsair]

Hi all.  Anyone know how to use `quad' to integrate a vector function?
I have the following code:

    global w = 2;
    global C = 0.2;
    global I = 1;
    global r0 = [2;0;5];
    
    function vr = r(t)
      global w;
      vr = [sin(w * t); cos(w*t); 0.8*t];
    endfunction
    
    function vt = tang(t)
      global w;
      vt = [w*cos(w*t); -1*w * sin(w*t); 0.8];
    endfunction
    
    function db = dB(t)
      global C I r0;
      db = C .* I .* cross(tang(t), r(t) - r0) ./ norm(r(t) - r0)^3;
    endfunction
    
    [v, ier, nfun, err] = quad("dB", 0, 12)

Running this script yield the following result:

    v = -0.041123
    ier = 0
    nfun =  399
    err =  1.5253e-09

With several screen of "warning: implicit conversion from real matrix
to real scalar".

What does this mean?  Why is `v' not a vector?

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