Nathan Bloomfield wrote: > Hello haskell-cafe; > > I'm fiddling with this > <http://cdsmith.wordpress.com/2009/07/20/calculating-multiplicative-inverses-in-modular-arithmetic/> > blog post about inverting elements of Z/(p), trying to write the > inversion function in pointfree style. This led me to try executing > statements like > > n `mod` 0 > > which in the ring theoretic sense should be n, at least for integers*. > (MathWorld agrees. <http://mathworld.wolfram.com/Congruence.html>)
I agree that (n `mod` 0) ought to be n. Specifically divMod n 0 = (0,n) and quotRem n 0 = (0,n) In (divMod n m) the sign of the remainder is always the same as the sign of m, unless n or m is zero. In (quotRem n m) the sign of the quotient is the product of the signs of n and m, unless n or m is zero. -- Chris _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
