Map Height in Pixels: INPUT[number:map_height_y]
Map Width in Pixels: INPUT[number:map_width_x]
lat: VIEW[{map_height_y} / 2][math]
long: VIEW[{map_width_x} / 2][math]
How Many Pixels In Scale: INPUT[number:scale_pixels]
How Many Units in Scale: INPUT[number:scale_pixels_range]
Scale: VIEW[1/({scale_pixels}/{scale_pixels_range})][math:mapCalc1]