code: def mxv(m1, vin):
      
      m1 = stypes.toDoubleMatrix(m1)
      vin = stypes.toDoubleVector(vin)
      vout = stypes.emptyDoubleVector(3)
      libspice.mxv_c(m1, vin, vout)
      return stypes.cVectorToPython(vout)
docs: Multiply a 3x3 double precision matrix with a
      3-dimensional double precision vector.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/mxv_c.html
  
      :param m1: 3x3 double precision matrix.
      :type m1: 3x3-Element Array of floats
      :param vin: 3-dimensional double precision vector.
      :type vin: 3-Element Array of floats
      :return: 3-dimensional double precision vector.
      :rtype: 3-Element Array of floats