I'm a beginner in all these stats, but I understand PE Ratio as displayed on google finance, e.g for BP.L it's nearly 6.
However the stat seems different in yahoo finance, because it's PE TTM, where it is reported as 363! Then they have a "forward" P/E but that seems different too.
So how can/should the P/E ttm be interpreted? I presume the TTM is key and is what difference is to google finance. But having looked around i'm struggling to see why / how it's calculated. How can I get the "normal" (by normal i mean the one everyone refers to in the news etc) PE ratio from yahoo finance API? Perhaps I have to calculate it myself?