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; vim: set ts=4 sw=4 et ft=idlang:
;+
; Greatest common divisor function
;-
function gcd, a, b
compile_opt idl2, hidden
j = a & k = b
while (finite(k) and (k /= 0)) do begin
t = j mod k
j = k
k = t
endwhile
return, a
end
;+
; Least common multiple funcion
;-
function lcm, a, b
compile_opt idl2, hidden
return, abs(a * b) / gcd(a, b)
end
pro rat::normalize
compile_opt idl2, hidden
n = gcd(abs(self.numerator), abs(self.denominator))
; Note: This only works in IDL >= 8.3
new_numerator = (self.numerator / n) * $
signum(signum(self.numerator) * signum(self.denominator))
new_denominator = self.denominator / n
self.numerator = temporary(new_numerator)
self.denominator = temporary(new_denominator)
end
function rat::numerator
compile_opt idl2, hidden
return, self.numerator
end
function rat::denominator
compile_opt idl2, hidden
return, self.denominator
end
pro rat::add, q
compile_opt idl2, hidden
n = lcm(self.denominator, q->denominator())
new_numerator = (n / self.denominator) * self.numerator + $
(n / q->denominator()) * q->numerator()
new_denominator = n
self.numerator = temporary(new_numerator)
self.denominator = temporary(new_denominator)
self.normalize
end
pro rat::sub, q
compile_opt idl2, hidden
r = obj_new('rat', -q->numerator(), q->denominator())
self.add, r
obj_destroy, r
end
pro rat::mul, r, q
compile_opt idl2, hidden
self.numerator = self.numerator * q->numerator()
self.denominator = self.denominator * q->denominator()
self.normalize
end
pro rat::div, q
compile_opt idl2, hidden
r = obj_new('rat', q->denominator(), q->numerator())
self.mul, r
obj_destroy, r
end
function rat::INIT, numerator, denominator
compile_opt idl2, hidden
if (n_params() eq 2) then begin
self.numerator = numerator
self.denominator = denominator
endif $
else if (obj_valid(numerator)) then begin
; numerator is actually a "rat" object
self.numerator = numerator->numerator()
self.denominator = numerator->denominator()
endif
return, 1
end
pro rat__define, class
compile_opt idl2, hidden
class = { rat, $
numerator: 0., $
denominator: 0. $
}
end
pro print_bottle, n, verbose=verbose
compile_opt idl2
on_error, 2
verbose = keyword_set(verbose)
!quiet = ~verbose
if (verbose) then begin
case (n) of
2: begin
print, n, format='(I0, 1X, "bottles of beer on the wall,")'
print, n, format='(I0, 1X, "bottles of beer.")'
print, format='("Take one down, pass it around,")'
print, format='("one last bottle of beer on the wall.", /)'
end
1: begin
print, n, format='("One last bottle of beer on the wall,")'
print, n, format='("one last bottle of beer.")'
print, format='("Take one down, pass it around,")'
print, format='("no more bottles of beer on the wall.", /)'
end
default: begin
print, n, format='(I0, 1X, "bottles of beer on the wall,")'
print, n, format='(I0, 1X, "bottles of beer.")'
print, format='("Take one down, pass it around,")'
print, n - 1, format='(I0, 1X, "bottles of beer on the wall.", /)'
end
endcase
endif
end
pro bottles
compile_opt idl2
on_error, 2
towels = 'Don''t Panic!'
nbottles = 99S
r = obj_new('rat', 1, 2)
q = obj_new('rat', 1, 6)
while (nbottles gt '0'XULL) do begin
print_bottle, nbottles
nbottles -= 1
endwhile
print, (towels ne '') ? towels : 'Panic!'
stop
r->sub, q
print, r->numerator(), r->denominator(), format='(I0, "/", I0)'
end
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