Name

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    QUAT2ROTAXIS

Purpose

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    Returns the net axis and angle of the rotation specified by the
    input quaternion.

Category

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    Math

Calling Sequence

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    Result = QUAT2ROTAXIS(Quat)

Inputs

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    Quat: A quaternion specifying a rotation.

Outputs

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    The function returns a 4-element vector. The first 3 elements are
    the axis of the rotation and the 4th element is the
    magnitude of the rotation in radians.

Example

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    IDL> theta=!PI/3.
    IDL> rm = [[COS(theta),0,-SIN(theta)],[0,1,0],[SIN(theta),0,COS(theta)]]
    IDL> quat = MATRIX2QUATERNION(rm)
    IDL> rotation = QUAT2ROTAXIS(quat)
    IDL> PRINT, rotation
          0.00000 -1.000000 0.00000 1.04720

Modification History

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    Written by: Jeremy Bailin
    27 Nov 2008 Released in JBIU