ID: 23746 Created on: May 30, 2004 20:51 Updated on: April 22, 2010 21:34

Least common multiple and greatest common factor
Summary:	The code shows how to quickly obtain the greatest common factor, and the least common multiple. Both functions are used when manipulating fractions, among others. Several methods are possible; the method usually taught in school involves prime numbers, but this code will execute much faster (and it is much simpler) than the use of prime numbers.
Rating:	Rate this entry
Created by:	Hilmar Zonneveld Independent Consultant Cochabamba

* Sample invocation:
? gcf(20, 30)
? lcm(20, 30)

function gcf(tnNumber1, tnNumber2)
	* Find the greatest common factor between two numbers
	* Note that in VFP, integer calculations are unreliable for large numbers.
	* I will illustrate the basic principle with an example.
	* Find the gcf of 14 and 10.
	* This gcf is the same as the gcf of 10 and 4, where 4 is obtained as 14-10.
	* Repeat until one of the numbers is divisible by the other.
	local lnTemp
	do while tnNumber2 # 0
		lnTemp = tnNumber1 % tnNumber2
		tnNumber1 = tnNumber2
		tnNumber2 = lnTemp
	enddo
	return tnNumber1
endfunc

function lcm(tnNumber1, tnNumber2)
	* Find the least common multiple of two numbers.
	* Note that in VFP, integer calculations are unreliable for large numbers.
	* The basic principle is simply this property:
	* The product of the greatest common factor and the least common multiple of two numbers
	* is equal to the product of the numbers themselves:
	* gcf(x,y) * lcm(x,y) = x * y
	* The int() is for display purposes only.
	return int(tnNumber1 * tnNumber2 / gcf(tnNumber1, tnNumber2))
endfunc

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