How does the computational cost of verifying transactions scale with the number of total transactions? As more transactions are added to the block chain, does each individual transaction (ie. I send a bitcoin to a friend) get more expensive (in terms of FLOPS) to verify and commit to the chain? If each new transaction cost does change the difficulty of verifying subsequent transactions, how does this scale?

I'd appreciate any answers, links or even location in the code where this happens. Thanks.

Reference: bitcoin wiki on confirmations
As more transactions are added to the block chain, does each individual transaction (ie. I send a bitcoin to a friend) get more expensive (in terms of FLOPS) to verify and commit to the chain?


No, it does not get more expensive in terms of anything. It especially does not get more expensive in terms of FLOPS because there are no floating point operations in Bitcoin.

The only cost of verifying a transaction is that it may cause the UTXO set as a whole to become larger, and as the UTXO set becomes larger, it becomes slightly harder to pull the necessary information from it to verify transactions. It does become harder to sync the blockchain as the UTXO set grows. Otherwise there is no compounding cost of verifying transactions as more transactions are added to the blockchain.