The investment opportunity cost in Islamic economics

In this paper the meaning of investment opportunity cost and its related meaning such as elimination rate and next optimal variant will be explained and proved. From Micro perception, investment opportunity cost in interest based economy with assumption perfect competition and long term is exactly the interest rate. On the other hand if we ignore the said assumption which means non - existence of a perfect competition in interest based economy and in interest free economy, investment opportunity cost in one project whould be the best yield rate of the other. From Macro perception, in which the opportunity cost of all investment projects are considered, interest rate is the opportunity cost of all projects on the assumption that we have a perfect competition market in a long term, but If we ignore the mentioned assumptions in both interest - based economy and interest free economy, investment have only elimination rate and not opportunity cost.