A method of examining cardiac electromagnetic activity over a heart for diagnosing the cardiac functions of the heart is disclosed. The method may include constructing a phase diagram of electromagnetic signals over a heart by collecting sets of time-dependent magnetic signals, determining the zeroth and the first derivations of each set of the magnetic signals at a given time, and categorizing the zeroth and the first derivations of the magnetic signals in either of the four phases: (+, +), (−, −), (+, −), (−, +). The method may also include monitoring a wave propagation of the magnetic signals.