The limit-state function is defined in the standard space and isoprobabilistic transformation is used internally.
oscillator_d6The function can handle a vector or a matrix with column vectors.
Echard, B and Gayton, N and Lemaire, M and Relun, N:
A combined Importance Sampling and Kriging reliability method for
small failure probabilities with time-demanding numerical models
Reliability Engineering and System Safety 111 232-240, 2013.