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%****************************************************************************%
% FILE : int_extra.ml %
% DESCRIPTION : Additional functions for integer arithmetic in ML. %
% %
% READS FILES : <none> %
% WRITES FILES : <none> %
% %
% AUTHOR : R.J.Boulton %
% DATE : 4th March 1991 %
% %
% LAST MODIFIED : R.J.Boulton %
% DATE : 12th April 1991 %
%****************************************************************************%
%----------------------------------------------------------------------------%
% Absolute value of an integer %
%----------------------------------------------------------------------------%
let abs i = if (i < 0) then (-i) else i;;
%----------------------------------------------------------------------------%
% Function to compute the remainder of an integer division %
%----------------------------------------------------------------------------%
ml_curried_infix `mod`;;
let n mod m =
let r = n - ((n / m) * m)
in if (r < 0) then (r + m) else r;;
%----------------------------------------------------------------------------%
% Function to compute the Greatest Common Divisor of two integers. %
%----------------------------------------------------------------------------%
let gcd (i,j) =
letrec gcd' (i,j) =
let rem = i mod j
in if (rem = 0)
then j
else gcd' (j,rem)
in (if ((i < 0) or (j < 0))
then fail
else if (i < j) then gcd' (j,i) else gcd' (i,j)
) ? failwith `gcd`;;
%----------------------------------------------------------------------------%
% Function to compute the Lowest Common Multiple of two integers. %
%----------------------------------------------------------------------------%
let lcm (i,j) = (i * j) / (gcd (i,j)) ? failwith `lcm`;;
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