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36 lines
725 B
Prolog
36 lines
725 B
Prolog
; docformat = 'rst'
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;+
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; Find the greatest common denominator (GCD) for two positive integers.
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;
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; :Returns:
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; integer
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;
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; :Params:
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; a : in, required, type=integer
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; first integer
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; b : in, required, type=integer
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; second integer
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;-
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function mg_gcd, a, b
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compile_opt strictarr
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on_error, 2
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if (n_params() ne 2) then message, 'incorrect number of arguments'
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if (~mg_isinteger(a) || ~mg_isinteger(b)) then begin
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message, 'integer arguments required'
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endif
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_a = abs(a)
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_b = abs(b)
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minArg = _a < _b
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maxArg = _a > _b
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if (minArg eq 0) then return, maxArg
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remainder = maxArg mod minArg
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if (remainder eq 0) then return, minArg
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return, mg_gcd(minArg, remainder)
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end
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