what is the formula to compute the price of forex?

for example,eurusd is 1.3000, next kick the price has changed to 1.2990;
How the price comes from?only by the trades happens?or the price is computed not only by the amount of the trades, it is also affected by some other variable?

Hi,

The movement of the price comes from the simultaneous buying and selling of currencies. In other words, it's moved by the forex market. Hope this clarifies. Are you a beginner in forex?


Regards,
Dan

Every Exchange just tries to maximize the amount of sellers and buyers at every price. That's the same if you go to your grocery store.
There is no orderbook that does the work but the invisible hand of the market.
If an Apple costs 60 Cents the price where one who produces the apple is satisfied because at that price the most apples are sold. And you are as a consumer satisfied to because that's the price where you would have bought the most apples.
That's the beauty of the market. Everyone just wants the best for themselfs and in the end everyone is satisfied.

http://en.wikipedia.org/wiki/Walrasian_auction
http://en.wikipedia.org/wiki/L%C3%A9on_Walras -> General Equilibrium Theroy

i am not a beginner,but i am wondering about how the price is gotten after 1 year's trade