def pxform(fromstr, tostr, et):
    """
    Return the matrix that transforms position vectors from one
    specified frame to another at a specified epoch.

    http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/pxform_c.html

    :param fromstr: Name of the frame to transform from.
    :type fromstr: str
    :param tostr: Name of the frame to transform to.
    :type tostr: str
    :param et: Epoch of the rotation matrix.
    :type et: float
    :return: A rotation matrix.
    :rtype: 3x3 Element Array of floats
    """
    et = ctypes.c_double(et)
    tostr = stypes.stringToCharP(tostr)
    fromstr = stypes.stringToCharP(fromstr)
    rotatematrix = stypes.emptyDoubleMatrix()
    libspice.pxform_c(fromstr, tostr, et, rotatematrix)
    return stypes.cMatrixToNumpy(rotatematrix)
Return the matrix that transforms position vectors from one
    specified frame to another at a specified epoch.

    http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/pxform_c.html

    :param fromstr: Name of the frame to transform from.
    :type fromstr: str
    :param tostr: Name of the frame to transform to.
    :type tostr: str
    :param et: Epoch of the rotation matrix.
    :type et: float
    :return: A rotation matrix.
    :rtype: 3x3 Element Array of floats