#EUL2JAC Euler angle rate Jacobian
#
# J = EUL2JAC(PHI, THETA, PSI) is a Jacobian matrix (3x3) that maps ZYZ Euler angle rates to 
# angular velocity at the operating point specified by the Euler angles PHI, THETA, PSI.
#
# J = EUL2JAC(EUL)  as above but the Euler angles are passed as a vector EUL=[PHI, THETA, PSI]. 
#
# Notes::
# - Used in the creation of an analytical Jacobian.
# - Angles in radians, rates in radians/sec.
#
# Reference::
# - Robotics, Vision & Control: Second Edition, P. Corke, Springer 2016; p232-3.
#
# See also rpy2jac, eul2r, SerialLink.jacobe.

# Copyright (C) 1993-2019 Peter I. Corke
#
# This file is part of The Spatial Math Toolbox for MATLAB (SMTB).
# 
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# in the Software without restriction, including without limitation the rights
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#
# The above copyright notice and this permission notice shall be included in all
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# https://github.com/petercorke/spatial-math

function J = eul2jac(phi, theta, psi)

    if length(phi) == 3
        # eul2jac([phi theta psi])
        theta = phi(2);
        psi = phi(3);
        phi = phi(1);
    elseif nargin ~= 3
        error('SMTB:eul2jac:badarg', 'bad arguments');
    end
J = [ 0, -sin(phi), cos(phi)*sin(theta)
      0,  cos(phi), sin(phi)*sin(theta)
      1,        0,           cos(theta) ];  
        
