obtenemos los
parametros =  [-0.54194872  0.34088326  8.83562194  3.64696014] y la matriz de covarianza es [[  1.37343117e-06   9.73774600e-07  -1.48608028e-06  -9.73914030e-10]  [  9.73774600e-07   2.40061432e-06  -2.44009190e-06  -8.21500762e-08]  [ -1.48608028e-06  -2.44009190e-06   3.71840568e-06   1.52791070e-08]  [ -9.73914030e-10  -8.21500762e-08   1.52791070e-08   3.98032502e-07]]