Life total changing

[Bulls on Parade]

I've been tempted to post this topic before, but this thread was really the impetus to do so now:

http://www.themanadrain.com/forums/viewtopic.php?t=18031

Is doubling a player's life total the same thing as making them gain life equal to their life total? The function imposed is obviously addition, but since it doesn't say "gain" or "add" anywhere on the card, I'm sort of skeptical.

Another group of cards to bring into question would be those that halve a player's life total. Do they cause a loss of life equal to half a player's life total?

Sorry if this topic seems juvenile because the answer is actually as obvious as it seems, but I'd really like to clear this up.

[Toad]

All life changes are made through life gain or loss of life. If you have 10 life and cast Beacon of Immortality, you will gain 10 life. If you are at 6 life at the end of your turn with Form of the Dragon on the board, you will lose 1 life.

That means Sulfuric Vortex will shut down Beacon of Immortality, for example.