Convert decimal number to rational: Difference between revisions
add RPL
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0.000001000001 = 1000001/1000000000000 ok</pre>
=={{header|RPL}}==
From HP-48 versions, conversion can be directly acheived with the <code>→Q</code> instruction. HP- models shall use instaed the following code, which is based on continuous fractions.
{{works with|Halcyon Calc|4.2.8}}
{| class="wikitable"
! RPL code
! Comment
|-
|
≪
ABS LAST SIGN 1E6 → sign dmax
≪ (0,1) (1,0)
'''DO'''
SWAP OVER 4 ROLL INV IP
LAST FP 5 ROLLD
* +
'''UNTIL''' DUP2 IM SWAP IM * dmax >
4 PICK dmax INV < OR '''END'''
ROT ROT DROP2
"'" OVER RE sign * →STR + "/" +
SWAP IM →STR + STR→
≫ ≫ '<span style="color:blue">'''→PQ'''</span>' STO'' STO
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<span style="color:blue">'''→PQ'''</span> ''( x → 'p/q' ) ''
store sign(x) and max denominator
a(0) = x ; hk(-2) = (0,1) ; hk(-1) = (1,0)
loop
reorder int(a(n)), hk(n-1) and hk(n-2) in stack
a(n+1)=1/frac(a(n)) back to top of stack
hk(n) = a(n)*hk(n-1) + hk(n-2)
until k(n)*(kn-1) > max denominator or
a(n+1) > max denominator
clean stack
convert a(n) from (p,q) to 'p/q' format
return 'p/q'
|}
.905405405405 <span style="color:blue">'''→PQ'''</span>
-3.875 <span style="color:blue">'''→PQ'''</span>
'''Output:'''
<span style="color:grey"> 2:</span> '67/74'
<span style="color:grey"> 1:</span> '-31/8'
=={{header|Ruby}}==
{{works with|Ruby|1.9+}}
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