Yes, the MTL.txt file contains all of the metadata that you need to duplicate the examples of cos(t) that I provided. You will find both gain and offset calibration factors to convert DN to either TOA radiance or TOA reflectance. You will also fin Sun Elevation to calculate the sun angle and you will find the Julian day to calculate Sun-Earth distance (d). Follow this user guide (second section) to understand how to convert data to TOA reflectance. http://landsat.usgs.gov/Landsat8_Using_Product.php
