File name: 'extractionyield.m'. Function for calculating
the extracted drug fraction in liquid-liquid extraction.
Four input arguments: 'n', 'V_a', 'V_b' and 'K'
One output argument: 'B'
n: Number of performed extractions
V_a: Volume of solvent A
V_b: Volume of solvent B
K: Distribution coefficient
B: Extracted fraction in solvent B
Input syntax: B = extractionyield(n,V_a,V_b,K)
Developed by Joris Meurs BASc
*Plot function add in which the total extracted fraction is plotted against the number of performed extraction