[net.math] A simple Diophantine Equation

bs@faron.UUCP (Robert D. Silverman) (10/11/85)

Does anyone know of a simple way for solving the diophantine equation:

	Ax + By + xy = K  with A,B,K given?

By making the substitution x' = (x + B) and y' = (y + A)  it can
be transformed into the problem of factoring K + AB.

Is there any other way of solving it????


Bob Silverman  (they call me Mr. 9)

gjk@talcott.UUCP (John) (10/14/85)

In article <364@faron.UUCP>, bs@faron.UUCP (Robert D. Silverman) writes:
> Does anyone know of a simple way for solving the diophantine equation:
> 
> 	Ax + By + xy = K  with A,B,K given?
> 
> By making the substitution x' = (x + B) and y' = (y + A)  it can
> be transformed into the problem of factoring K + AB.
> Is there any other way of solving it????

I don't think there is a better way.  Not only is it true that if you factor
K + AB, you get an x and a y, but also if you manage to get an x and a y
(by some other means), you get a factorization of K + AB with little addi-
tional computation.  Therefore the problems are essentially equivalent.
-- 
abcdefghijklmnopqrstuvwxyz
      ^  ^^

andrews@yale.ARPA (Thomas O. Andrews) (10/15/85)

In article <364@faron.UUCP> bs@faron.UUCP (Robert D. Silverman) writes:
>
>Does anyone know of a simple way for solving the diophantine equation:
>
>	Ax + By + xy = K  with A,B,K given?
>
>By making the substitution x' = (x + B) and y' = (y + A)  it can
>be transformed into the problem of factoring K + AB.
>
>Is there any other way of solving it????
>
>
>Bob Silverman  (they call me Mr. 9)

If,in fact, there was a nicer way to solve this problem, then one would
also be able to quickly factor K+AB.  If anyone out there has a fast algorythm
for solving this equation, I'm sure the government would like to see it. :-)
In any event, the two problems (solution of the equation and factorization)
are basically equivalent, so there can't be a much better way to solve it ....


-- 
					      Thomas Andrews

17?  My dear, what worthless, superstitious nonsense!