def rot_axis1(theta):
    ct = cos(theta)
    st = sin(theta)
    lil = ((1, 0, 0),
           (0, ct, st),
           (0, -st, ct))
    return Matrix(lil)

###############
# Functions
###############
Returns a rotation matrix for a rotation of theta (in radians) about
dataset/ETHPy150Open sympy/sympy/sympy/matrices/dense.py/rot_axis1