A pilot flying under LAX Class B entered ONT Class C at 4;000 FT after his iPad failed and he lost situational awareness.

Narrative

I was flying with another airplane westbound north of Ontario Class C with a final destination to the southwest. I split with the other aircraft and was going to fly southeast under the LAX Class B. I confused another airport with ONT and was further east than I thought. I was previously using an iPad with moving map software to identify my position but this system quit working (GPS receiver went dead even though it was connected with ship power. This unit has failed). My main concern was to stay away from LAX Class B and so I went further east to make sure I was well clear. I realized that I had entered the Class C and I was not talking to anyone. I exited Class C as quickly as possible. I am in the habit of talking to en-route controllers for advisories. I was not doing so because I had been flying with another aircraft and had not yet called in. Additionally; I was counting on a portable display that quit working. I should have flight planned better; and entered waypoints into the aircraft's panel GPS to maintain situational awareness.