MATLAB: How to display quaternion number

quaternion

Hello,

I want to dispaly a quaternion number as q= 1+2i+3j+4k .But the code is not working.

Here the code;

q=quaternion(1,2,3,4);

this is the error;

Undefined function 'quaternion' for input arguments of type 'double'.

Anybody can help me please?

Best Answer

q = quaternion([1 2 3 4])

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MATLAB: Does conversion from quaternions to rotation angles followed by rotation angles to quaternions give different results in Aerospace Toolbox 2.2(R2008b)

This is an expected behavior in Aerospace Toolbox 2.2(R2008b) in the way the quaternion to rotational angle conversion is executed.

When a call is made to QUAT2ANGLE, q is normalized internally using the QUATNORMALIZE function. The input q is changed to qin (q/norm(q)).

However, when a call is made using the ANGLE2QUAT to reconvert the rotational angles back to quaternions, the denormalization is not done. Hence, the output 'q' is does not appear same as input 'q' but it is actually the normalized version of 'q' (qin).

As a workaround, one can denormalize the ouput to match the input.

q=[1 0 1 0];
[yaw, pitch, roll] = quat2angle(q)
q2 = angle2quat(yaw, pitch, roll)
q3 = q2*norm(q);

Output (q3) is now [1 0 1 0] , same as the input (q) was [1 0 1 0].

MATLAB: How to threshold only real part of a complex matrix

>> A = complex(randi([-3,3],4,4),randi([-3,3],4,4)) % fake data
A =
  -2 + 3i  -2 + 1i   2 - 3i  -2 + 1i
  -2 + 0i   3 + 0i  -3 + 3i   0 + 0i
   2 + 0i   2 - 2i   3 + 3i   0 - 3i
   1 - 2i  -3 - 2i   3 + 2i   0 - 2i
>> B = complex(real(A).*(real(A)<=0.5),imag(A)) % set real(A)>0.5 to 0.
B =
  -2 + 3i  -2 + 1i   0 - 3i  -2 + 1i
  -2 + 0i   0 + 0i  -3 + 3i   0 + 0i
   0 + 0i   0 - 2i   0 + 3i   0 - 3i
   0 - 2i  -3 - 2i   0 + 2i   0 - 2i

Best Answer

Related Solutions

MATLAB: Does conversion from quaternions to rotation angles followed by rotation angles to quaternions give different results in Aerospace Toolbox 2.2(R2008b)

MATLAB: How to threshold only real part of a complex matrix

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